CMC Triggers M-Lok 4-Piece Accessory Kit, Fits M-LOK, Anodized Finish, Includes (1)-3 Slot Rail, (1)-5 Slot Rail, (1)-7 Slot Rail, (1)-QD Sling Mount, Black 81724 Designed for use with all M-LOK compatible handguards and forends" M-LOK aluminum rail sections allow the attachment of various 1913 Picatinny spec rail-mounted accessories such as lights" vertical grips" etc. Designed for use with all M-LOK compatible handguards and forends" M-LOK aluminum rail sections allow the attachment of various 1913 Picatinny spec rail-mounted accessories such as lights" vertical grips" etc.