Jacobs 33371 JK 200 J3 Industrial Grade Keyless Chuck 5.0 to 20.0 Millimeter Capacity with No.3 Jacobs Taper Mount Automatic fitting for efficient, fast change of tools Machine fitting via DINO238 of Jacobs tapers and UNF thread fittings Self-tightening feature for maximum gripping power Wide range capacity Each chuck 100-Percent inspected for performance and precision