The Lee Breech Lock system allows reloaders to quickly change between dies. These quick change bushings with lock ring eliminator collar help to provide unmatched precision and convenience when adjusting dies. The split clamp positively locks reloading dies into position. These extra bushing allow the reloader to read more quickly and easily change dies in a matter of seconds. Just give the bushing a small twist and remove from the press. more info Dies fit inside here the bushing and stay intact with the setting for the next reloading session saving valuable setup time.