The JBO Thread Plug Gauge is a precision tool designed for metric fine threads. Its Go/No-Go design lets you quickly verify hole acceptance, helping ensure parts thread together Cleanly and reliably. Ideal for machinists, quality control teams, assembly technicians, and hobbyists working with metric threads, this gauge speeds inspection without sacrificing accuracy.

• Go/No-Go Quick Checks for Fast, Confident Acceptance: Clearly defined Go and No-Go ends let you confirm correct thread fit at a glance, reducing inspection time and guesswork while supporting consistent results.
• Metric Fine Thread Spec: M21 x 1, 4H Tolerance: Precisely sized for the M21 x 1 fine thread with 4H tolerance, ensuring compatibility with standard metric components and reliable mating every time.
• Hardened Steel Construction with Durable Knurl: Built to endure daily workshop use, the hardened steel resists wear and the knurled grip provides secure handling in oil, coolant, or grime-prone environments.

Designed for reliability in busy shops, this plug gauge helps you streamline setup, cut downtime, and achieve repeatable thread measurements. Its robust construction preserves accuracy across production runs, while its compact form fits neatly into your gauge set or tool chest for ready access during assembly and quality checks.