BMT40 with Y Axis 12 Station Live Turrets have a serrated shaft that is inserted into an opening on the face of the turret. The tool is held in place by a mating part with teeth that are housed inside the turret. ; When an Allen wrench is used to tighten the locking screw, located on the face of the turret, the mechanism applies clamping pressure that holds the tool securely in place. The holder is kept from twisting by a pin that is located on the mounting surface of the turret. http://www.baowei-china.com/live-turret/bmt40-with-y-axis-12-station-live-turret.html