This sling swivel stud with machine screw thread and nut 2 pack are designed to allow the user to attach sling accessories such as rifle slings, swivels and Bipods to their firearms. Machine Screw Sling Swivel Studs and Nuts come 2 per pack with polymer spacer washer. Provides solid foundation for anchoring slings in hollow stocks and forends with backer nut. Made from steel, 7/8" long shaft.