JBO Thread Plug Gauge - UNC Go-No/Go - Left Hand - 2B - No. 4 x 40 FHH Whether refining an existing hole

Whether refining an existing hole or dialing in a precise diameter

while the straight shank and standard holder compatibility simplify setup and workflow across CNC and manual machines

Built in high-speed steel (M2)

and tapered neck supports precise detailing

while the order-to-delivery model ensures you receive a tool built to Toolex quality with a predictable lead time

JBO Thread Plug Gauge - UNC Go-No/Go - Left Hand - 2B - No. 4 x 40 FHH Whether refining an existing holeThe JBO Thread Plug Gauge is a precision tool for verifying No. 4 x 40 (4 40) left hand UNC threads. Designed for inspectors, machinists, and technicians across manufacturing, automotive, and aerospace environments, it helps ensure threaded holes and mating parts conform to Unified thread standards with speed and accuracy. Featuring a 2B tolerance grade and a robust go no go design, this gauge delivers fast pass fail checks, reduces inspection