Magpul MOE Polymer Rail Section, 9 Slots, Black. Size L4 (9 Slots), max overall length of 4.1". Mounting screw center-to-center of 2.4". Designed for use with MOE Hand Guards, Forends, and many standard plastic hand guards, the MOE Polymer Rail Sections allow the attachment of various 1913 Picatinny spec rail-mounted accessories such as lights, vertical grips, etc. Injection molded from a proprietary reinforced composite for enhanced strength and durability while remaining lightweight, Rail Sections also feature beveled ends to reduce snagging and eliminate sharp corners and edges. All hardware necessary for attachment directly to integral mounting slots on MOE Hand Guards is included.