Threaded ring gauges are round metal rings that are threaded on the inside to a nominal size. They are used to check whether externally threaded parts and fasteners are within tolerance. The adjustment mechanism for adjustable threaded ring gauge consists of a locking assembly, sleeve, and adjustment screw. Go (Plus) rings have a slightly larger pitch diameter, and if the externally threaded part mates cleanly, then it passes the Go test. The No-Go (Minus) ring has a slightly smaller pitch diameter, and if the externally threaded part mates cleanly, it is out of tolerance and fails the test. All gauges are marked with nominal size and gauge type, and are right-handed unless stated otherwise.