Spence Industries, Inc. is proud to partner with Leader Corporation of Shelby Township, MI as a third party A2LA Accredited Laboratory. Precision JO-PLUG® thread grinding and calibration is performed in accordance with ISO/IEC 17025:2017 general requirements and ANSI/NCSL Z540-1-1994 and R205.

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Precision JO-PLUG® pitch diameters are calibrated using a Pratt & Whitney Super Mic utilizing the universal "three-wire method."

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Precision JO-PLUG® "lead and trail" thread angles are verified using a J&L Metrology Optical Comparator.