Spline drive Breech Lock Bushings 4 pack. New, easy grip splined drive surface allows easy, accurate and fast die installation in your press. Reloading dies are confusingly similar looking, so we anodized and colored the bushings so you can “color code” your dies for quick positive identification. No need for lock rings on your dies with these quick-change bushings. Simply lightly tighten the hex clamp screw, and split collar will put a vise lock on your die. Loosen the screw, and the die will spin freely.