7.7601"-8.5100" (197.11Mm-216.15Mm) Tool Steel Class Z Go (Minus) Ring Gage. Class Z, Bright Tool Steel, Go (Minus) Custom Steel Ring Gage. Perfect For Use As Masters For Bore Gages And Internal Micrometers. Use Vermont Gage Ring Gages To Efficiently Inspect External Dimensions Of Manufactured Parts. With A Go And Nogo Ring, An Inspector Can Quickly Pass/Fail Parts Without Taking Time Consuming Readings From An Indicator. Available In Master (Bi-Lateral Tolerance), Go (Minus Tolerance) Or No-Go (Plus Tolerance). Nist Traceable. Certificate Of Accuracy Included. Vermont Gage Usa Part #231419110. At Checkout, In The 'Additional Instructions' Field, Specify The Ring Gage Inside Diameter Within The Range Specified.