AS-S2W03SL Innovative Low Profile Swivel Stud Picatinny/Weaver Rail Adaptor with 3 Slots, Integrated with Quick Detachable Sling Swivel mounting Base Mounts on the Swivel Stud of your Rifle Innovative Design Makes It Much More Stable Than Regular Swivel Stud Adaptor Adjustable Rail-Levelness Provides Up to 10o Degree Angle Compensation in order to Keep the Rail Surface as Much as Parallel to the Barrel Low Profile Picatinny/Weaver Mounting Deck with 3 Slots Quick and Easy Installation