- The Dead Air 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 Series or Key-Mo equipped supressor to your rifle. If you’re not quite ready to turn up the silence, you can still employ the finest brake on the market and experience a flatter shooting rifle with minimal concussion compared to traditional muzzle brakes. When it comes to removal, the suppressor can be easily removed without carbon-locking onto the mount. Timing shims are not included.