0.5101"-0.8250" (12.96Mm-20.95Mm) Tool Steel Class Y No-Go(Minus) Master Setting Disc, Style 1 With End Grips Class Y,Bright Tool Steel,No-Go(Minus) Master Setting Disc Custom Master Setting Discs. Use These Vermont Gage Master Setting Discs To Calibrate Your Measuring Equipment. Designed To Satisfy Traceability Requirements Of Your Quality Control System, These Masters Are A Must For Your Calibration Lab And Inspection Areas. Available In Master (Bi-Lateral Tolerance), Go (Plus Tolerance) Or No-Go (Minus Tolerance). Vermont Master Setting Discs Are Available In Three (3) Styles And Come Complete With Grips And Certificate Of Accuracy. Vermont Gage Usa Part #251304310. At Checkout, In The 'Additional Instructions' Field, Specify The Gage Size Within The Range Specified.