A highly common application for gages is inspecting threaded holes and shafts. While using plug gages to check threaded holes in manufactured parts is a popular practice, checking shaft, dowel and fastener diameter using ring gages is perhaps less common but equally important. There are also smooth ring gages for checking non-threaded parts.

Ring gages provide a go/no-go assessment of the specified dimensional tolerances or attributes of pins, shafts, or threaded studs. Ring gages are used for comparative gaging as well as for the checking, calibrating or setting of gages or other standards in a wide variety of industries, including machine tool, automotive, oil and gas exploration, and other metal working applications.