Spline drive Breech Lock Bushings 2/pack. New, easy grip splined drive surface allows easy, accurate and fast die installation in your press. No need for lock rings on your dies with these quick-change bushings. Simply lightly tighten the clamp screw, and split collar will put a vise lock on your die. Loosen the screw, and the die will spin freely. Once set you'll never lose position.