kwa km4 m4 m16 sr10 full metal 2gx aeg airsoft bb rifle gun(Airsoft Gun) KWA 2GX Gearbox / Semi / Full Auto selective fire / Adjustable Hop-Up KWA 2G High Performance Bucking / Free Float MIL-SPEC-1913 [Picatinny] Full metal alloy receivers / Flat top receiver Rail Adapter System / Adjustable front / rear sight 6 position collapsible stock with integrated battery compartment