The JBO Thread Ring Gauge (GO) for UNC external threads is a precision inspection tool designed for machinists, quality teams, and assembly technicians. Sized for No. 4 x 40 with a right-hand thread and 2A class accuracy, it enables fast, reliable verification of external thread diameters to UNC standards. Whether you’re on a production line, in a workshop, or in a quality lab, this GO gauge helps confirm that parts will thread correctly and assemble without fit issues.

Manufactured from hardened steel, this ring gauge delivers long-lasting durability and wear resistance in demanding environments. The knurled outer surface provides a secure grip for quick handling, even while wearing gloves, so inspections stay smooth and precise.

• Go Gauge for UNC External Threads: Confirms the No. 4 x 40 UNC external thread meets the minimum diameter, delivering fast pass/fail checks and reducing rework.
• Hardened Steel Construction: Built to endure heavy use, resisting wear to maintain accurate measurements over time.
• Ergonomic, Knurled Design: Offers a secure grip and easy alignment, improving handling and speeding up inspections—even with gloves.

This gauge helps streamline quality control by providing clear, repeatable results that support consistent thread fit across parts and assemblies. By investing in a reliable GO gauge, you reduce downtime, minimize rejects, and create a measurable standard for your production lines.