Thread Ring Gages are used to ensure the external threads conform to the Class of Fit requirements. Both a Go Ring and Not Go Ring are required. Thread Ring Gages are used to check external threaded parts. Typically they conform to either 2A or 3A classes of fit. The part being checked is acceptable if it does not enter more than 3 turns.
Ring gages are furnished with Standard class “X†industry tolerance
For rings with class “W†tolerance pitch diameters, set plugs must be ordered or provided