JET 561709 TDC-750, Taper Mount Drill Chuck 1/8"-3/4" x JT-4 Heat treated high grade alloy steel Chuck jaws are precision fitted to withstand 115 PSI of torque without distraction Meets JIS Specification: B4634E T.I.R. at chuck nose under .001 Capacity 1/8"-3/4" JT-4 Taper Mount