The listing, Dunlop Duel Design Straplok has ended.
This is a strap retainer for guitar and bass players. Quoted from the back of the box, "The Dunlop Straplok System is the strap retainer with the artist in mind. 360 degree groove and ball design allows the unit to rotate without catching. The case is hardened steel skin guarentees long life. Interchangeable strap buttons allow the same strap can be used with several guitars. Release tested up to 800lbs. of pull, Dunlop Straploks will not come loose under normal playing conditions.