Plain ring gauges are used for:
Inspecting the external diameters of manufactured parts
Checking shafts and cylindrical parts that do not have threads or a spline cut along the surface
Setting electronic bore gages, air gages, internal micrometers, and length measuring instruments
Checking the external diameters of straight round parts
Plain ring gauges can quickly pass or fail parts without the need for taking readings with a conventional measuring instrument. For example, if a go ring gauge does not fit on the part being tested, it means that the part diameter is too large and contains excess material, and must be rejected for rework.