Accusize Tools - 4'' (100 mm) 5C Precision Lathe Chuck 3-Jaw Selfcentering Scroll, 0225-0234 Works with any 5C tooling the body is made of cast Iron, the Jaws are made of steel. The T.I.R less than 0.1mm, The body hardness is HBW 187-220 The Jaw hardness is HRC 53 - HRC 55