Features: Self-locking function breaks the traditional locking methods, with strong clamping force, more effective in preventing the workpiece loose. Unique thrust bearing makes it easy to convert the torque applied by hand into greater clamping force. Good metal texture, comfortable coat surface. Fit with 1/2-20UNF shank adapter. Suitable for electric drill, electric screwdriver, etc. Specification: Clamping range: 2-13mm (1/16-1/2) Connection size: 1/2-20UNF Package list: 1 * Drill Chuck