The JBO Thread Plug Gauge is a precision tool designed for metric fine threads, helping you verify threaded holes quickly and confidently. Built for engineers, machinists, quality inspectors, and shop environments, this left-hand Go/No-Go gauge checks tolerance for M40 x 2 threads (6H) so parts mate smoothly on first assembly.
Constructed from hardened steel, the gauge delivers dependable performance and stands up to daily use in demanding workshop conditions.

• Fast, Go/No-Go thread checks: Quickly confirm holes meet the M40 x 2, 6H spec, reducing guesswork and speeding setup and inspection.
• Left-hand compatibility: Specifically designed to inspect left-hand threads, ensuring accurate validation for components that use this orientation.
• Durable, hardened steel build: Withstands frequent handling and wear, preserving accuracy and extending service life in busy workshops.

By using this plug gauge, you streamline quality assurance, cut rework, and improve assembly reliability. The combination of precise Go/No-Go checks and a rugged build helps technicians work faster with greater confidence, delivering consistent thread engagement and fewer returns or fit issues across your manufacturing or maintenance workflows.