Free Float Rifle RAS PN:21318 The KAC Rifle Length Free Float RAS (Rail Adapter System) features full length mil-spec M1913 Picatinny rails at the 12-, 3-, 6-, and 9 o'clock positions, 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. Rifle Requirements: 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 fore end 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. Specifications Weight: 16.3oz Length: 12a ^2