JBO Thread Plug Gauge – UNJF Go/No-Go, Left Hand, 3B, 5/16 x 24 is a precision inspection tool designed to verify internal threads quickly and reliably. Built for machinists, quality teams, and shops that service manufacturing, automotive, and aerospace components, this gauge helps ensure UNJF-thread holes meet spec before assembly or production runs.

• Go/No-Go Verification for UNJF Threads: Quickly identify conforming vs. non-conforming left-handed threads without dismantling parts, speeding setup and reducing guesswork.
• Exact UNJF Left-Hand Specs (5/16 x 24, 3B): Precisely matched to the specified thread form and class to ensure accurate sizing checks and consistent results across production.
• Rugged, Easy-Grip Design: Knurled, corrosion-resistant body and durable ends withstand busy shop environments for repeated use and reliable measurements.

This plug gauge helps streamline quality control, reduce downtime, and prevent misfits in threaded assemblies by delivering clear pass/fail results on the shop floor. With its compact, dual-ended design, you can perform quick verification checks on the bench or in the field, giving you confidence that your 5/16 x 24 UNJF left-hand threads meet the required 3B tolerance every time.