Magpul Industries Rail Section, Fits M-LOK Hand Guard, Aluminum, 5 Slots MAG581-BLK Designed for use with all M-LOK compatible Hand Guards and Forends" M-LOK Aluminum Rail Sections allow the attachment of various 1913 Picatinny spec rail-mounted accessories such as lights" vertical grips" etc. Machined from milspec-anodized aluminum" M-LOK Rail Sections also feature beveled ends to reduce snagging and eliminate sharp corners and edges. All hardware necessary for attachment directly to M-LOK Slots on either aluminum or polymer hand guards and forends is included. 5 Slots" max overall length of 2.5". Made in U.S.A.