An accessory used with tapping spindle and tapping machine, suitable for taps with round and four corners, stirring knives and other tools. It can be subdivided into torsion collets, rigid non-torque collets, and fixed collets. There are various specifications and sizes to choose from. It is a locking device that clamps a tool or workpiece, and its function is to lock the connection between the tool and the spindle. Usually used on drilling and milling machines and machining centers.