Compatible with sling swivel studs (or similar type mounts) and standard 1.25" wide slings, to include the Magpul(R) RLS and MS1(R) Slings. The Locking Sling Swivel is constructed of high-strength solid steel with a black oxide finish for corrosion resistance. Its steel locking sleeve attaches to the mount and provides a secure fit, while still allowing it to rotate smoothly. Additionally, the locking sleeve's ergonomic knurling ensures a more positive grip when tightening or loosening the sleeve on the mount.