The Tin Star USA S2S M4 is an excellent CQB rifle for anyone who wants a durable, full-metal AEG. Sporting the Tin Star logo, the full metal upper and lower receiver house a metal one piece hop up unit and 8mm Metal Reinforced Version 2 Gearbox with M110 Spring. Designed with a functional bolt catch, the hop up can be easily adjusted during play. The rear flip-up SCAR-style sight is removable to be replaced or used in conjunction with aftermarket optics. The front flip-up sight is integrated into the RIS front rail. The rail system allows for attachment of lights, lasers, optics, grips, cameras and more. It also features a quick-detach sling mount location. The multi-position crane stock provides a comfortable fit for nearly all operators and holds the included 9.6v nunchuck style NiMH battery. Fires at 370 FPS with 0.20g BBs.