The JBO Thread Plug Gauge is a precision tool designed to quickly verify UNF threads, specifically the left-hand variant of 1/4 x 28, with a 2B tolerance. It’s ideal for inspectors, machinists, and quality teams across manufacturing, automotive, and aerospace environments, helping you confirm threaded holes meet universal standards and are ready for use in critical assemblies.

• Go/No-Go quick checks: The simple go/no-go design lets you instantly distinguish conforming from non-conforming threads, speeding up inspections and reducing guesswork in daily QA workflows.
• Left-Hand UNF 1/4 x 28 with 2B tolerance: Precisely matched to the left-hand thread and 2B class tolerances, delivering reliable measurements and consistent fit verification for compatible components.
• Durable, user-friendly construction: Knurled grip and robust ends provide secure handling and long-lasting use in busy workshops, helping readings stay clear and repeatable over time.

Using this gauge helps you streamline thread verification, minimize rework, and maintain tight quality control. Its clear Go/No-Go feedback supports faster decision-making, improving overall workflow and ensuring reliable performance in demanding applications.