Model 450 4'' DIA Air Chuck with Special hardened and ground jaws to grip O.D. of a precision split bushing. The bushing is Special hardened and ground to locate on .8683 part diameter. Bushing has an O.D. of approximately 1.800 inches to clear flange. Bushings are made of alloy steel with I.D. and O.D. ground at the same time to insure tight tolerance runout run out.