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 and has an adjustable cheek-rest with a built-in dual Picatinny rails.