FAB Defense GL-Shock Buttstock is a recoil-reducing stock for M4/M16 platforms, featuring a patented shock-absorbing mechanism with a built-in premium chrome silicon alloy spring. Compatible with both Mil-Spec and Commercial aftermarket buffer tubes via its patented Anti-Rattle Mechanism. Constructed from durable, lightweight fiberglass-reinforced polymer in matte black finish, OAL 7.08, height 5.11, width 1.69, weighing 10.72 oz. No protruding parts to snag on gear or brush. Includes a rubber butt pad, molded-in rear storage compartment, and ambidextrous quick-release sling-swivel ports. Safety note Follow all manufacturer installation instructions. Verify proper function and secure mounting before use. Comply with local firearm laws and regulations.