Pro R8 ER-32 Collect Chuck with Drawbar End ~ Made of 20CrMnTi alloy steel ~ Electrolysis nickel coating ~ Premium hardened & all ground body for extended tool life. ~ Thread of Drawbar End: MT3 – 1/2-13. ~ Maximum RPM is 8,000 ~ T.I.R. <= .0002″ ~ Superior Finish Made of 20CrMnTi alloy steel with electrolysis nickel coating Premium hardened & all ground body for extended tool life. Thread of Drawbar End: MT3 – 1/2-13. Maximum RPM is 8,000 T.I.R. <= .0002″