TROY Industries M4 Sling Mount, Black Finish, Quick Detach Swivel SMOU-M4S-00BT-00 The Troy OEM M4 Sling Mount replaces the factory M4 carbine receiver end plate" incorporating ambidextrous quick detach swivel mounts. Includes heavy-duty quick detach push button swivel. Made from hardened aircraft aluminum with stainless steel push button.