JBO Thread Plug Gauge is a precision Go/No-Go gauge designed for metric fine internal threads. This left-hand version is tuned for M18 x 0.5 with a 6H tolerance, making it ideal for quality-critical holes in machining, assembly, and maintenance tasks.

Built for real-world shop use, the gauge features a knurled body for a secure grip and ends machined to exact Go/No-Go specifications. Crafted from hardened steel, it delivers long-lasting wear resistance in daily inspection workflows.

• Swift Go/No-Go verification: quickly confirm whether a hole falls inside the 6H tolerance for M18 x 0.5 LH threads, speeding up inspection and reducing guesswork.
• Durable hardened steel construction: engineered for heavy use, resisting wear and maintaining accurate checks over time in busy environments.
• Left-hand metric fine threading compatibility (M18 x 0.5, 6H): specifically designed for LH applications, ensuring precise, repeatable measurements and reliable fit verification.

This gauge helps you streamline quality control, minimize downtime, and ensure consistent results across shifts. By delivering clear pass/fail feedback for left-hand M18 x 0.5 holes, it supports faster decisions, fewer reworks, and dependable assembly outcomes.