The M-LOK mounting system allows you to mounts to all M-LOK compatible handguards and forends, attach just about anything to your rail system without having to remove the rail itself. Its universal, and it makes it possible for you to mount only what you need, and exactly where you need it. The 4-Piece Accessory Kit contains- 1 M-LOK QD Sling Mount that accepts any push button QD swivel, 1 M-LOK 3 Slot Picatinny Rail, 1 M-LOK 5 Slot Picatinny Rail, and 1 CMC M-LOK 7 Slot Picatinny Rail. Beveled edges reduce snagging, anti-rotation design prevents swivels from spinning. Mounting hardware included.