Spi 34-375-6 Plug Thread Gage 1/4-20 2B Double End

Product Description

The SPI 34-375-6 is a double-end plug thread gage designed to verify internal thread conformance to 1/4-20 UNC specifications at 2B tolerance class. One end carries the Go member; the opposite end carries the No Go member. The Go end confirms the thread falls within the minimum material condition, while the No Go end confirms it does not exceed the maximum material condition. A size 1 handle is included. This gage is used by machinists, quality control inspectors, and precision tradespeople to ensure threaded holes meet dimensional standards before assembly or final inspection.

This gage is suited for inspection of 1/4-20 internally threaded workpieces in manufacturing, fabrication, and quality assurance environments. The double-end configuration allows both Go and No Go checks without switching tools, reducing inspection time on production floors or field verification tasks. The included NIST-traceable certification supports use in regulated or contract manufacturing settings where documentation of measurement traceability is required.

Key Features

• Double-end design combines Go and No Go gages in a single tool
• Checks 1/4-20 UNC internal threads to 2B tolerance class
• NIST-traceable traceability certification included
• Steel construction for durability and dimensional stability
• Size 1 handle included — no separate handle purchase required

Compatibility

Designed for inspection of 1/4-20 UNC internally threaded holes conforming to 2B class tolerance.

Installation Notes

Thread plug gages are inspection tools, not cutting tools — do not force the Go end into a threaded hole. A correctly formed thread should accept the Go end with hand pressure only. Keep gages clean and lightly oiled when stored to prevent corrosion that could affect calibration. Periodic recalibration against a certified reference standard is recommended in high-volume or regulated inspection environments.