Dead Air DA102: Available for standard 7.62x51mm and 5.56 45 threaded barrels, the Keymount Muzzle Brake is your gateway to silence. When you re ready for peace and quiet use the Keymount brake to quickly attach your Sandman-L or Sandman-S to your rifle. If you re not quite ready to turn up the silence, you can still employ one of the finest brakes on the market and experience a flatter shooting rifle with minimal concussion compared to traditional muzzle brakes.