The Threadmaster Screw Plug Gauges are precision Go/No-Go gauges designed for verifying the accuracy and quality of internal metric threads (M3–M12) in accordance with Class 6H tolerance standards. Each gauge ensures that threaded holes meet strict engineering specifications, providing reliable pass/fail inspection in production, maintenance, and quality control settings. Supplied with a certificate of conformity, these gauges offer traceable verification for high-precision work.