The revolutionary patented gl-shock absorbing buttstock contains an "anti-rattle" recoil-reducing mechanism with a built in premium silicon chrome alloy spring creating a state-of-the-art stock for your m4/m16.Made from mill-spec reinforced polymer composite, the stock is compatible with both mil-spec and commercial tubes and has watertight battery storage for two cr123a 3v lithium batteries or aa 1.5v.It features an integral ribbed rubber butt pad with a non-slip design and quick detach sling swivel connectors on both sides.This model has a black finish.Type: ButtstockFirearm Type: RifleFirearm Model: M4/M16Material: PolymerFinish: BlackSwivel Studs: Yes