Ring gauge

A ring gauge, or ring gage, is a cylindrical ring of a thermally stable material, often steel, whose inside diameter is finished to gauge tolerance and is used for checking the external diameter of a cylindrical object.

Individual ring gauges or ring gauge sets are made to variety of tolerance grades in metric and English dimensions for master, setting, or working applications.

No-go or not-go gauges provide a precision tool for production comparative gauging based on a fixed limit.

Similar to gage blocks, ring gauges are sold under different accuracy grades.

The higher the grade, the lower the allowable variance from the nominal diameter.