This new GEMTECH Viper-45 suppressor is for the .45 MAC. It has an over-diameter heat shield, knurled to make it more controllable. The heat shield doubles as a secure locking device that ratchets back into a rock-solid mount to prevent loosening or dangerous unscrewing during hard use. The Viper is the quietest dedicated suppressor available for one of the most widespread submachine guns ever marketed in the United States. ALL NFA RULES APPLY.