The unique quick detachable design stops the metal swivel body from contacting the gun. The close machining tolerances provide smooth and silent operation. Included is a special adapter for Beretta 390 magazine cap; adapter also included for most pump and auto magazine caps; wood screw base for butt-stock.The magnum quick detach super swivels from Uncle Mikes are as solid of a foundation to attach a sling as you can find. These QD super swivels are designed to take a beating from shotgun rounds to heavy recoiling rifle rounds, these swivels will hold. Features: Includes special adapter for Beretta 390 magazine cap Adapter also included for most pump and auto magazine caps Wood screw base for butt-stock Does not fit Browning 2000, Winchester 1400, Ithaca 37, Savage 30, Sears 21 or Stevens pumps