The JBO Thread Plug Gauge is a metric fine Go/No-Go gauge designed to verify internal threads with precision. It’s built for machinists, inspectors, and assembly teams working with M21 x 1 right-hand threads (6G) to quickly validate hole acceptance, even in high-volume productions. The hardened-steel construction delivers durable, long-lasting performance in tough shop environments.

• Go/No-Go precision for metric fine threads: Quickly determine if a tapped hole meets the M21 x 1 right-hand 6G tolerance using distinct go and no-go checks, reducing guesswork and rework.
• Specialized for M21 x 1 right-hand threads: Precisely matched to this metric fine thread form to ensure consistent, reliable fits in critical assemblies.
• Durable, wear-resistant hardened steel: Built to withstand daily use, maintaining accuracy and extending gauge life in demanding workshop conditions.

This gauge speeds up quality control by providing clear pass/fail results, helping your team avoid misfits during assembly and save time on recalibration. With its textured, knurled body for secure handling, you’ll get repeatable measurements across batches and shifts, giving you confidence in every threaded connection.