Umarex COLT M4 4.5mm. Amazing air gun by UMAREX, a replica of the M4, the weapon of the American army. It features a synthetic stock and forearm with metal parts on the body. It is a break barrel and accepts a 4.5mm pellet. It operates with a spring and to cock it, you break the barrel. Its sights are adjustable, it has a weaver base for a scope, and the safety is in the classic position as on the real one, for greater ease of use. The magazine is for effect. The Umarex COLT M4 4.5mm is an amazing air gun ready to win the favor of all shooters.