JBO Thread Plug Gauge is a left-hand, metric coarse, go/no-go plug gauge designed to verify M30 x 3.5 threaded holes. Built for engineers, buyers, tradespeople, and hobbyists, it provides a fast, reliable check that ensures holes will accept components before assembly.
This hardened steel gauge delivers consistent inspections and long service life in demanding workshop environments.

• Fast, go/no-go verification: Quickly confirm whether a threaded hole meets the M30 x 3.5 coarse-thread standard, speeding up quality checks and reducing rework.
• Durable hardened steel construction: Withstands daily use and wear, maintaining accuracy over thousands of inspections in busy shops.
• Left‑hand thread variant for compatible applications: Optimized for left-hand threaded components, ensuring precise checks where standard gauges may not apply.

This plug gauge supports streamlined workflows by delivering clear pass/fail results, helping you avoid incorrect fittings and downtime. Its robust build and precise tolerances empower consistent quality across assemblies, making it a dependable, long-term addition to any metrology or maintenance toolkit.