Daniel Defense MFR Rail M-Lok QD Sling Mount, Compatible Only with Daniel Defense MFR Rail, Omega Rail, and the DELTA 5 Stock, Not Compatible with Any Other M-LOK Rail, Steel Construction, Phosphate Coated Finish, Black 03-021-15136 The MFR Rail M-Lok QD Sling Mount, designed specifically for the Daniel Defense MFR Rail, allows for ambidextrous attachment of the popular push button sling swivel. This limited-rotation accessory mounts at designated points at the front and rear on both sides of the MRF Rail system for tangle-free attachment of slings. This product is only compatible with the MFR Rail, Omega rail and the DELTA 5 Stock. It is not compatible with MFR XL Rail, DD5 Rail, or any other manufacturers M-LOK rail system