Limestone ParagonX vs Lafayette LX7: 2026 Comparison

How These Systems Are Related

When professional polygraph examiners compare the Limestone ParagonX and the Lafayette LX7, they are evaluating two distinct product lines that share a corporate parent. Lafayette Instrument Company acquired Limestone Technologies Inc. on August 12, 2022 [1]Verified Branford Castle Partners Acquires Polygraph Bolt-on (Limestone Technologies Acquisition Announcement)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022, and that Limestone was a Canada-based polygraph manufacturer. This acquisition was announced by Branford Castle Partners, the New York-based private equity firm that owns Lafayette [1]Verified Branford Castle Partners Acquires Polygraph Bolt-on (Limestone Technologies Acquisition Announcement)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022, and that Limestone was a Canada-based polygraph manufacturer. Since the acquisition, Limestone Technologies has operated as a subsidiary of Lafayette Instrument Company, with both brands maintaining their separate product identities [2]Verified Limestone Technologies Homepage
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022.

Prior to the acquisition, Limestone Technologies was an independent Canada-based manufacturer of polygraph equipment headquartered in Kingston, Ontario [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies was headquartered in Kingston, Ontario, Canada. The company was well-known for its Polygraph Professional Suite software, which it introduced in 2003 [4]Verified Limestone Technologies LinkedIn — Polygraph Professional Suite History
Confirms Polygraph Professional Suite was introduced in 2003 and became internationally recognized. Both Lafayette and Limestone have decades of experience serving the credibility assessment community [1]Verified Branford Castle Partners Acquires Polygraph Bolt-on (Limestone Technologies Acquisition Announcement)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022, and that Limestone was a Canada-based polygraph manufacturer.

Understanding this corporate relationship is important for purchasing decisions. Rather than choosing between two competing manufacturers, examiners are selecting between two complementary product lines within the same corporate family. Both systems benefit from Lafayette's manufacturing infrastructure, support network, and ongoing investment in polygraph technology. If you are starting a private polygraph practice, knowing these options share a common support parent is reassuring.

Lafayette Instrument Company: Over 75 Years of Innovation

Lafayette Instrument Company was established in 1947 by Max Wastl, a German immigrant who studied Electrical Engineering at Purdue University [5]Verified Lafayette Instrument Company History
Confirms Lafayette was established in 1947 by Max Wastl with one employee in Lafayette, Indiana. The company started with a single employee and a small shed in Lafayette, Indiana [5]Verified Lafayette Instrument Company History
Confirms Lafayette was established in 1947 by Max Wastl with one employee in Lafayette, Indiana. The first catalog was printed in 1954 [6]Verified Lafayette Instrument Company — Our Story
Confirms the company's history from first polygraph in 1972 through LX series evolution, and through Max Wastl's leadership, Lafayette quickly became the market leader in psychophysiological instrumentation for schools and university laboratories [6]Verified Lafayette Instrument Company — Our Story
Confirms the company's history from first polygraph in 1972 through LX series evolution.

Lafayette Instrument Company is today recognized as the world's leading manufacturer of polygraph instrumentation and equipment, distributing credibility assessment instruments to private examiners, government, and military organizations around the world [7]Verified Lafayette Instrument Company Homepage
Confirms Lafayette is the world's leading manufacturer of polygraph instrumentation and equipment. One authorized reseller has claimed Lafayette holds approximately 85% of the global polygraph market share, with instruments preferred by examiners in more than 80 countries [8]Verified Polygraph Investigative Services — Lafayette Market Share
Reports Lafayette holds approximately 85% global polygraph market share with instruments used in 80+ countries. The company has over 75 years of experience engineering data acquisition and measurement instrumentation [9]Verified Lafayette Instrument Company — About (75+ Years)
Confirms Lafayette has over 75 years of experience in data acquisition instrumentation.

Lafayette produced its first polygraph instrument in 1972 [10]Verified Lafayette Polygraph Company News — First Polygraph in 1972
Confirms Lafayette produced its first polygraph in 1972 and has distributed more credibility assessment instruments than any other manufacturer. Since then, the company has distributed more credibility assessment instruments worldwide than any other manufacturer [10]Verified Lafayette Polygraph Company News — First Polygraph in 1972
Confirms Lafayette produced its first polygraph in 1972 and has distributed more credibility assessment instruments than any other manufacturer. The company's polygraph product evolution includes the LX1000 prototype, the LX2000, LX3000, LX4000, LX5000, LX6, and now the LX7 [11]Verified Lafayette Polygraph — Our Story (LX Series History)
Confirms the evolution of Lafayette polygraph products from LX1000 through LX7. For a deeper look at how polygraph technology has evolved, the journey from analog chart recorders to today's digital systems is remarkable.

Limestone Technologies: The Canadian Innovator

Limestone Technologies' corporate office was originally located in Kingston, Ontario, Canada [3]Verified Limestone Technologies Inc. LinkedIn Profile
Confirms Limestone Technologies was headquartered in Kingston, Ontario, Canada. The company built its reputation on software engineering and biofeedback instrumentation, with its primary focus on developing products for security and public safety [12]Verified Lafayette Instrument — Limestone Technologies Description
Describes Limestone as a software and biofeedback instrumentation solutions provider focused on security and public safety. Limestone is best known for its Polygraph Professional Suite software, introduced in 2003, which became internationally recognized as a leading polygraph solution [4]Verified Limestone Technologies LinkedIn — Polygraph Professional Suite History
Confirms Polygraph Professional Suite was introduced in 2003 and became internationally recognized.

In 2017, Limestone Technologies acquired the Backster School of Lie Detection, a polygraph school founded by the renowned Cleve Backster in 1959 [13]Verified Lafayette Instrument Co. Acquires Limestone Technologies — AntiPolygraph.org
Confirms Limestone Technologies acquired the Backster School of Lie Detection in 2017 and Lafayette launched PEAK in 2016. This expanded Limestone's footprint into training and education.

The August 2022 acquisition by Lafayette expanded Lafayette's product line and market reach [1]Verified Branford Castle Partners Acquires Polygraph Bolt-on (Limestone Technologies Acquisition Announcement)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022, and that Limestone was a Canada-based polygraph manufacturer. Lafayette's president Jennifer Rider noted that bringing the two companies together would achieve their collective potential and maximum effectiveness [1]Verified Branford Castle Partners Acquires Polygraph Bolt-on (Limestone Technologies Acquisition Announcement)
Confirms Lafayette Instrument acquired Limestone Technologies on August 12, 2022, and that Limestone was a Canada-based polygraph manufacturer. Today, Limestone operates as a subsidiary focused on the ParagonX hardware platform and Polygraph Pro Suite software, while sharing Lafayette's manufacturing, distribution, and support infrastructure [2]Verified Limestone Technologies Homepage
Confirms Limestone Technologies became a subsidiary of Lafayette Instrument Company in August 2022.

Limestone ParagonX: High-Resolution Data Acquisition

The ParagonX is designed for the professional polygraph examiner who requires data acquisition software and physiological hardware [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. The system offers dual-channel 32-bit analog-to-digital resolution, delivering high-fidelity signal capture [15]Verified ParagonX Product Page — 32-bit Resolution
Confirms ParagonX offers high retention USB to dual channel 32-bit resolution. At a native 625 samples per second per channel, the ParagonX has the highest sampling rate in any polygraph instrument [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included — a significant technical advantage for capturing subtle, rapid physiological changes.

Accurate data acquisition begins with Lemo precision connectors [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. The ParagonX Acquisition System uses only flush-mounted Lemo connectors for all nine inputs [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. These medically approved connectors are made of nickel-plated brass, and each connector is key-aligned to ensure easy, concise connections [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. Lemo connectors employ a patented push-pull latching system for ruggedized, secure connections [16]Verified ParagonX Upgrade Page — Lemo Connectors Detail
Confirms Lemo precision connectors with patented push-pull latching system for ruggedized connections.

The ParagonX system connects to the examiner's laptop via USB and includes a standard sensor package: an EDA kit with gold-plated metal electrodes and Ag/AgCl disposable electrodes, a blood pressure cuff assembly with adjustable cuff, cardio tubing, and sphygmomanometer [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. Understanding how each polygraph channel measures physiological data is essential when evaluating these hardware specifications.

Lafayette LX7: Next-Generation 10-Channel System

The LX7 is Lafayette's next-generation polygraph system, boasting features designed to elevate accuracy, consistency, and usability in the field [17]Verified LX7 Polygraph System Product Page
Confirms LX7 is next-generation system with improved PPG sensor and LXEdge compatibility. The system is a 10-channel polygraph with a comprehensive accessories package [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff.

The LX7 employs Fischer connectors with a quick release mechanism, rated for twice the mating cycles of connectors used by other manufacturers [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. Electronic sensors cannot be incorrectly connected, reducing setup errors [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. The LX7 features a curved design that improves cable management and organization for a cleaner workspace [19]Verified LX7 System Upgrade — PAT Measurement
Confirms LX7 PAT measurement capability, improved PPG sensor, and curved connector design.

A standout feature of the LX7 is its improved detection of subtle, rapid changes in pulse blood volume via the photoelectric plethysmograph (PPG) sensor, delivering more reliable cardiovascular readings across a broader selection of examinees [17]Verified LX7 Polygraph System Product Page
Confirms LX7 is next-generation system with improved PPG sensor and LXEdge compatibility. The system also calculates Pulse Arrival Time (PAT) — the time between the ECG pulse and PPG waveform — providing a measurement directly correlated to blood pressure [19]Verified LX7 System Upgrade — PAT Measurement
Confirms LX7 PAT measurement capability, improved PPG sensor, and curved connector design. Research has found that PAT is as effective as the cardiograph for discriminating between truthful and deceptive people [19]Verified LX7 System Upgrade — PAT Measurement
Confirms LX7 PAT measurement capability, improved PPG sensor, and curved connector design. For more on cardiovascular measurement, see our guide to polygraph cardiograph channels.

Lafayette also offers the LX6, a 10-channel system that shares many accessories with the LX7 and continues to be available for examiners who prefer its feature set [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. Both the LX6 and LX7 are designed for portability, with Lafayette-branded backpacks that fit laptops up to 16 inches and dedicated protective pouches for the DAS unit [20]Verified Lafayette New Products Page — Protective Pouches
Confirms protective pouches supporting LX7, LX6, LX5000, and Paragon Series systems.

Pneumograph (Respiratory) Sensors

Both product lines include dual pneumograph components for measuring thoracic and abdominal respiration — a standard requirement since research demonstrated that deception-related respiratory changes may appear primarily in the chest or abdomen depending on the individual.

The LX7 uses color-coded pneumo assemblies (blue and titanium) compatible with both the LX6 and LX7 [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. These pneumatic assemblies feature venting capabilities [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. The ParagonX also includes dual pneumograph components as part of its standard system package [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. Understanding these respiratory measurements is central to reading a polygraph chart.

Electrodermal Activity (EDA) Sensors

Electrodermal activity — measuring changes in skin conductance caused by sympathetic nervous system activation — is one of the most sensitive channels for detecting deception. Our detailed guide on galvanic skin response in polygraph testing covers the science behind this measurement, while understanding EDA in plain language explains how it works for non-specialists.

The ParagonX includes an EDA kit with 10-foot EDA leads, gold-plated metal electrodes, and packages of Ag/AgCl disposable electrodes [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. The LX6/LX7 EDA assembly has been designed for maximum efficiency and serviceability, including an EDA cable plus reusable snap electrodes and disposable electrodes [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. Lafayette has highlighted that the LX6/LX7 features best-in-industry electronics and EDA [21]Verified Lafayette Instrument LX6 Brochure (PDF)
Confirms LX6-S bundle designation, 10 data channels, Fischer connectors, and OSS-3 compatibility.

Cardiovascular Sensors

Both systems include blood pressure cuff assemblies for cardiovascular measurement. The ParagonX package includes an adjustable blood pressure cuff assembly with cardio tubing and sphygmomanometer [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included.

The LX6/LX7 uses a standard Kovacic-style blood pressure cuff that eliminates problems associated with loosely wrapped cuffs and ensures the cuff does not shift away from the brachial artery during application [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. The center of the bladder is clearly marked on both inner and outer surfaces for correct application on either right or left limb [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff.

The LX7's major cardiovascular innovation is its improved PPG sensor for enhanced pulse blood volume detection [17]Verified LX7 Polygraph System Product Page
Confirms LX7 is next-generation system with improved PPG sensor and LXEdge compatibility and the PAT measurement capability that supports research and further development as an eventual replacement for the traditional cardio measurement [19]Verified LX7 System Upgrade — PAT Measurement
Confirms LX7 PAT measurement capability, improved PPG sensor, and curved connector design.

Activity & Movement Sensors

Both systems include activity sensors designed to detect deliberate or involuntary movement during testing, which is important for identifying potential countermeasure attempts. The LX6/LX7 activity sensor provides a graphic record of movement, allowing the polygraph examiner to observe responses that may not have been seen during direct observation [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. The ParagonX similarly offers activity sensors as part of its product ecosystem [22]Verified Lafayette Polygraph Products Page
Confirms full product lineup including LX7, LX6, ParagonX, LX5000, Paragon, and DataPac Series.

Lafayette also offers specialized foot activity sensors and arm activity sensors for more granular movement monitoring on both the LX7 and ParagonX platforms [22]Verified Lafayette Polygraph Products Page
Confirms full product lineup including LX7, LX6, ParagonX, LX5000, Paragon, and DataPac Series.

Polygraph Pro Suite (Limestone/ParagonX)

Designed specifically for Limestone Technologies series polygraph systems, the Polygraph Pro Suite software offers a user-friendly design providing polygraph examiners with a range of time-saving features packaged into an easy-to-navigate front-end management system [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation. The software requires a valid Limestone Technologies polygraph serial number for download [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation.

The Polygraph Pro Suite FrontEnd stores and organizes all polygraph examinations in an easy-to-manage format [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation. Key features include post-test chart review with a range of scoring utilities and algorithms, auto-fill standardized report templates, and comprehensive digital storage of all examination data [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation.

A signature feature is the ChartSync utility, which Limestone describes as an innovation that changed the way examiners review examinations [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation. ChartSync synchronizes video, audio, and chart data for comprehensive chart review, and has since become an industry standard [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation. System requirements include an Intel 7th Generation or newer processor, a digital sound card for multimedia capabilities, and a digital video camera for video capture [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation. For examiners who conduct field examinations, the robust multimedia integration is particularly valuable.

LXSoftware (Lafayette LX Series)

LXSoftware is Lafayette's Windows-based polygraph software platform, offering what the company describes as unparalleled ease of use and proven reliability [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support. Current versions are compatible with Lafayette LX4000, LX5000, LX6, and LX7 systems [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support, providing a consistent software experience across multiple hardware generations.

LXSoftware is bundled with the Objective Scoring System version 3 (OSS-3) scoring algorithm [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support, one of the most validated computerized scoring systems in the polygraph field. The software also supports the Masseter Headphone System [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support and Mac compatibility via Parallels or other virtualization software [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support.

The software includes several specialized analysis tools. The RLE tool measures the ratio of the relevant response divided by the comparison response and produces a suggested pneumograph score [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support. The manual score sheet integration formulates printable reports and summary conclusion paragraphs for both event-specific and multi-issue exams [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support. This structured approach is especially valuable for examiners conducting PCSOT monitoring and maintenance polygraph tests.

LXEdge: The Next-Generation Software

Lafayette has released LXEdge, its next-generation polygraph software [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available. Designed with the future in mind, LXEdge is compatible with the Lafayette LX6 and LX7 along with the Limestone Paragon series [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available — making it the first software platform that bridges both product lines.

LXEdge offers many of the key features of LXSoftware with major updates to improve the efficiency of the examination process [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available. The software requires a valid LX7, LX6, ParagonX, or Paragon serial number for download [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available. Display requirements include a high-definition (1280 x 720) display greater than 15.6 inches diagonally with at least 8 bits per color channel [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available.

Lafayette offers online LXEdge training to help examiners transition to the new platform [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available. The availability of LXEdge as a cross-platform solution means that examiners using either hardware line can now access the same modern software environment.

The OSS-3: Validated Computerized Scoring

The Objective Scoring System version 3 (OSS-3) is one of the most significant scoring algorithms in modern polygraph practice. Developed by Raymond Nelson, Donald Krapohl, and Mark Handler (2008), the OSS-3 is a powerful computer algorithm that calculates a probabilistic classifier for both diagnostic and screening polygraphs [26]Verified Objective Scoring System – Version 3 Official Information
Confirms OSS-3 is based on sound polygraph testing principles with demonstrable validity across multiple validation samples.

The OSS-3 is a form of 7-position scoring where individually assigned values are derived from ratios based on measurements of the "Kircher features" [27]Verified Objective Scoring System (OSS) — British Polygraph Society Glossary
Confirms OSS is 7-position scoring based on Kircher features ratios that eliminates subjectivity in chart interpretation. Because scores come from measurements rather than subjective evaluations, the OSS eliminates subjectivity in chart interpretation [27]Verified Objective Scoring System (OSS) — British Polygraph Society Glossary
Confirms OSS is 7-position scoring based on Kircher features ratios that eliminates subjectivity in chart interpretation. These features were first introduced by researchers at the University of Utah during the 1980s and include the amplitude of increase for electrodermal and cardiovascular activity, along with reduction of respiration activity [28]Verified Brute-Force Comparison: A Monte Carlo Study of the OSS-3 and Human Polygraph Scorers
Confirms OSS-3 demonstrated balanced sensitivity and specificity with reduced inconclusives vs. previous versions, validated on N=292 and N=100 confirmed field cases.

Validation research has been extensive. In a brute-force Monte Carlo comparison study, OSS-3 demonstrated balanced sensitivity and specificity and provided significant improvements over previous OSS versions, including reduced inconclusive results and increased sensitivity to deception [29]Verified Brute-Force Comparison: OSS-3 Validation — Kircher Features Description
Confirms Kircher features were introduced at University of Utah in 1980s and include EDA amplitude, cardiovascular activity, and respiration reduction. In a separate criterion validity study using the USAF Modified General Question Technique, the OSS-3 computer algorithm produced 90.2% correct decisions with only 1.0% inconclusives [30]Verified Criterion Validity of ESS and OSS-3 with USAF MGQT
Confirms OSS-3 produced 90.2% correct decisions with 1.0% inconclusives in USAF MGQT validation study. This compared favorably to manual ESS scoring at 88.2% accuracy with 18.3% inconclusives [30]Verified Criterion Validity of ESS and OSS-3 with USAF MGQT
Confirms OSS-3 produced 90.2% correct decisions with 1.0% inconclusives in USAF MGQT validation study.

The OSS-3 is bundled with LXSoftware on Lafayette systems [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support and has also been made available to the broader polygraph community [26]Verified Objective Scoring System – Version 3 Official Information
Confirms OSS-3 is based on sound polygraph testing principles with demonstrable validity across multiple validation samples. Research on comparison question test methodology — the largest meta-analysis ever conducted on the CQT, analyzing 138 datasets — provides essential context for understanding how scoring algorithms interact with test formats [31]Verified A Comprehensive Meta-Analysis of the Comparison Question Polygraph Test
The largest meta-analysis ever conducted on the CQT, analyzing 138 datasets with meta-analytic effect size of 0.69.

Polygraph Pro Suite Scoring

The Polygraph Pro Suite software includes a range of scoring utilities and algorithms [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation for post-test chart review. While specific algorithm documentation is less publicly detailed than the OSS-3, the software provides examiners with tools to review charts and apply scoring methods.

Research by Honts and Reavy (2015) comparing CQT methods found substantial main effects of guilt in both OSS2 computer and human scoring, providing context for how both computerized and manual scoring approaches perform across different platforms [32]Verified The Comparison Question Polygraph Test: A Contrast of Methods and Scoring
Found substantial main effects of guilt in both OSS2 computer and human scoring across CQT variants. The foundational work by Kircher, Horowitz, and Raskin (1988) on the CQT meta-analysis laid essential groundwork for the algorithmic approaches used in modern polygraph software [33]Verified Meta-Analysis of the Comparison Question Test
First meta-analysis of the CQT, foundational work for computerized scoring approaches.

Manual Scoring Support

Both platforms support manual scoring, which remains a fundamental skill for all professional polygraph examiners. The American Polygraph Association and virtually all standard-setting bodies emphasize that computerized algorithms should supplement — not replace — examiner judgment. Both Polygraph Pro Suite and LXSoftware allow examiners to compare their manual scores with computer-generated scores, a best practice that enhances examination quality.

Setup & Sensor Attachment

Both systems are designed for efficient setup in both office and field environments. The ParagonX connects via USB with its nine Lemo-connector inputs providing reliable, key-aligned connections [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included. The LX7's Fischer connectors with quick-release mechanisms and error-proof electronic sensor connections offer rapid attachment and detachment [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff.

For examiners who frequently travel to conduct field examinations, portability matters. Both platforms are laptop-based systems with compact DAS units. Lafayette offers dedicated protective pouches supporting LX7, LX6, LX5000, and Paragon Series polygraph systems [20]Verified Lafayette New Products Page — Protective Pouches
Confirms protective pouches supporting LX7, LX6, LX5000, and Paragon Series systems, along with branded backpacks for laptops. Proper equipment shipping and handling is also important for traveling examiners.

Test Protocol Support

Both software platforms support the major polygraph test formats used in professional practice, including the Zone Comparison Test (ZCT), Modified General Question Test (MGQT), and various relevant/irrelevant formats. Understanding the role of irrelevant questions in polygraph testing and single-issue test formats helps examiners select the right protocol for each case.

Research by Offe and Offe (2007) investigated the theoretical mechanisms underlying comparison question test effectiveness, providing evidence for the psychological processes that drive accuracy across all platforms [34]Verified The Comparison Question Test: Does It Work and If So How?
Investigated theoretical mechanisms underlying CQT effectiveness and provided experimental evidence for psychological processes driving accuracy. Field studies by Ginton (2017) comparing different types of comparison questions in real criminal investigations have further validated the practical effectiveness of these techniques [35]Verified Examining Different Types of Comparison Questions in a Field Study of CQT Polygraph Technique
Field study providing evidence for practical effectiveness of both exclusive and non-exclusive comparison questions.

Quality Control & Reporting

Both platforms generate professional reports. LXSoftware uses manual score sheet data to formulate printable reports and summary conclusion paragraphs for event-specific and multi-issue exams [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support. The Polygraph Pro Suite provides auto-fill standardized report templates and comprehensive session documentation [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation.

For agencies requiring supervisory review, both platforms store complete examination records digitally. The LX7's compatibility with both LXSoftware and LXEdge provides flexibility in workflow optimization.

Institutional Adoption

Lafayette Instrument Company's products are widely used across the polygraph training community. Lafayette launched the PEAK Credibility Assessment Training Center in 2016 [36]Verified Lafayette PEAK Credibility Assessment Training Center Launch
Confirms PEAK was launched in 2016 for credibility assessment training, providing APA-accredited training. Following the 2022 acquisition, Limestone's training relationships, including the Backster School of Lie Detection acquired in 2017 [13]Verified Lafayette Instrument Co. Acquires Limestone Technologies — AntiPolygraph.org
Confirms Limestone Technologies acquired the Backster School of Lie Detection in 2017 and Lafayette launched PEAK in 2016, are also part of the Lafayette family.

The Chicago Polygraph Institute, for example, offers its students instruments manufactured by Lafayette Instrument Company [37]Verified Chicago Polygraph Institute — Products
Confirms CPI uses Lafayette Instrument Company polygraph systems for student training. Both the LX6-S and LX5000-SW are among the models used in training programs. For those considering becoming a polygraph examiner, selecting a system aligned with your training school's platform can provide a smoother learning experience.

Since LXEdge is compatible with both the LX6/LX7 and the Limestone Paragon series [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available, students trained on either platform can transition between systems with minimal disruption. This cross-compatibility is a significant advantage of both product lines being under the same corporate umbrella.

Pricing Models

Neither Lafayette nor Limestone publishes retail pricing on their websites — professional polygraph equipment is sold through direct quotation and authorized distributors. Lafayette offers leasing options for the LX6, with monthly payments that the company states can be covered after a few examinations, with full ownership after 36 months [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff. Lease arrangements include a full DAS warranty for the life of the lease and one-year warranty on system accessories [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff.

Based on secondary market data, a new Lafayette LX5000 system was listed at $5,995 in 2017 [38]Verified Colorado Polygraph Association — LX5000 System Listing
Confirms a Lafayette LX5000 system was originally priced at $5,995 when purchased from Lafayette in 2017, and used Stoelting CPS Pro instruments with approximately 1,100 tests have been listed at around $3,250 on the APA classifieds [39]Verified APA Classifieds — Equipment For Sale/Trade
Lists used Stoelting CPS Pro at $3,250 and shows demand for Limestone Paragon/ParagonX systems. Professional computerized polygraph systems from leading manufacturers generally range from the mid-thousands upward depending on configuration and accessories [40]Verified Polygraph Machine Prices: Basic to Advanced Systems
Reports professional polygraph equipment ranges from basic models at $1,500–$3,000 to high-end models up to $20,000. For context on export regulations that may affect international purchasing, see our dedicated guide.

Both systems offer trade-in programs. Lafayette allows examiners to trade in their current polygraph system to receive discounts on new LX7 or ParagonX systems [41]Verified Lafayette LX7 / ParagonX Trade-In Program
Confirms Lafayette offers trade-in discounts for examiners upgrading to new systems.

Long-Term Value Considerations

A critical advantage of both systems being under Lafayette's umbrella is long-term vendor stability. Lafayette Instrument Company has been in continuous operation since 1947 [5]Verified Lafayette Instrument Company History
Confirms Lafayette was established in 1947 by Max Wastl with one employee in Lafayette, Indiana, providing confidence that spare parts, repairs, software updates, and technical support will be available for years to come.

The LXEdge software platform's compatibility with both the LX6/LX7 and Paragon series [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available means that an investment in either hardware platform provides access to the latest software innovations. Examiners who start with one system and later want features from the other can potentially bridge the gap through software upgrades rather than full hardware replacement.

Where Other Manufacturers Fit

While this comparison focuses on the Lafayette/Limestone product lines, examiners should be aware of other options in the market. Stoelting Company, which has been manufacturing polygraph instruments since 1930, offers the CPS Elite — its fourth-generation computerized polygraph system featuring a built-in LCD touchscreen display, CPS Fusion software, and both piezo and mechanical pneumograph options [42]Verified Stoelting CPS Elite Polygraph System
Confirms Stoelting Elite is fourth-generation computerized polygraph with built-in LCD touchscreen, CPS Fusion software, and piezo respiration sensors. The CPS Elite replaced the earlier CPSpro system [42]Verified Stoelting CPS Elite Polygraph System
Confirms Stoelting Elite is fourth-generation computerized polygraph with built-in LCD touchscreen, CPS Fusion software, and piezo respiration sensors. For more details, see our Stoelting CPSpro Fusion Software review and our complete Stoelting product line guide.

The broader professional polygraph market also includes Axciton Systems and other manufacturers. However, Lafayette's stated position as the world's leading manufacturer of polygraph instrumentation [7]Verified Lafayette Instrument Company Homepage
Confirms Lafayette is the world's leading manufacturer of polygraph instrumentation and equipment, combined with the Limestone subsidiary, gives the combined Lafayette family arguably the broadest product range in the industry.

Choose the ParagonX If...

The Limestone ParagonX may be the better choice for examiners who prioritize maximum sampling resolution and data acquisition fidelity. With 32-bit dual-channel A/D resolution and 625 samples per second per channel [14]Verified ParagonX Polygraph System Product Page
Confirms ParagonX specifications: 625 samples per second per channel, 9 Lemo inputs, EDA and blood pressure cuff included[15]Verified ParagonX Product Page — 32-bit Resolution
Confirms ParagonX offers high retention USB to dual channel 32-bit resolution, the ParagonX offers the highest raw data capture capability in the industry. Examiners who value Lemo precision connectors (a standard in medical instrumentation) and who are already comfortable with the Polygraph Pro Suite ecosystem will find the ParagonX a natural fit.

The ParagonX is also worth considering for examiners involved in research programs or quality assurance activities where maximum data fidelity is paramount. Its ChartSync multimedia integration [23]Verified Polygraph Pro Suite Software Product Page
Confirms Polygraph Pro Suite features including ChartSync, session management, scoring utilities, and report generation makes it strong for comprehensive examination documentation.

Choose the LX7 If...

The Lafayette LX7 may be the better choice for examiners who want the latest-generation hardware from the established Lafayette brand. The LX7's improved PPG sensor for cardiovascular readings [17]Verified LX7 Polygraph System Product Page
Confirms LX7 is next-generation system with improved PPG sensor and LXEdge compatibility, PAT measurement capability [19]Verified LX7 System Upgrade — PAT Measurement
Confirms LX7 PAT measurement capability, improved PPG sensor, and curved connector design, and 10-channel architecture [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff make it a powerhouse for diverse examination needs.

The LX7's bundled OSS-3 algorithm [24]Verified LXSoftware Product Page
Confirms LXSoftware is bundled with OSS-3, compatible with LX4000/LX5000/LX6/LX7, and includes RLE tool and Masseter support — with its extensive published validation data including 90.2% correct decisions in criterion validity studies [30]Verified Criterion Validity of ESS and OSS-3 with USAF MGQT
Confirms OSS-3 produced 90.2% correct decisions with 1.0% inconclusives in USAF MGQT validation study — provides strong scientific defensibility for agencies that must demonstrate the basis of their testing methodologies. Examiners working in federal, state, or law enforcement settings where Lafayette hardware is already the institutional standard will benefit from seamless compatibility with existing workflows and the LX7's Fischer quick-release connectors designed for rapid, error-proof sensor attachment [18]Verified LX6 Polygraph System Product Page
Confirms LX6 is a 10-channel system with Fischer connectors, leasing options, and Kovacic-style blood pressure cuff.

The LXEdge Bridge

For examiners uncertain between the two platforms, the availability of LXEdge as a cross-compatible software solution [25]Verified LXEdge Software Product Page
Confirms LXEdge compatibility with LX6, LX7, and Limestone Paragon series, with online training available provides an important consideration. Regardless of which hardware you choose, LXEdge compatibility ensures access to Lafayette's latest software innovations and examination workflow tools.