Jacobs 30532 JKT 100-J33 High Torque/High Precision Keyless Chuck with 0.5 to 10.0 Millimeter Capacity and No.33 Jacobs Taper Mount. Precision tested and certified to .0016-Inch T.I.R. maximum at half capacity All parts are hardened for maximum accuracy and rigidity. Furnished with milled wrench flats and spanner wrench to allow the application of supplementary gripping torque Self-tightening feature for maximum gripping power For CNC machining centers in drilling, boring, counter-boring and milling operations requiring heavy penetration