Knights Armament Co.'s Mid-Length Free Float RAS Forend Assembly features full length mil-spec M1913 Picatinny rails making it compatible with any number of rail-mounted tactical accessories. The rail free floats the barrel, allowing for consistent barrel harmonics upon firing, and thus increased accuracy potential. Includes three KAC 11 Rib Rail Panels. This Free Float RAS requires that the rifle have a carbine or mid length gas system and a low profile gas block. Disassembly of the rifle's gas system and removal of the factory barrel nut will be necessary. This forend uses a proprietary barrel nut that may be installed using a standard AR-15 armorer's barrel nut wrench (sold separately). For AR-15/SR-15 based platforms only; not compatible with SR-25 variants. Installation instructions are included.