The Faxon Slim 3-Port Muzzle Brake solves a problem that has plagued legal firearms owners for years. When taking a barrel to the minimum legal limit with a permanently attached muzzle device, one was forever locked in to their barrel, gas block, and handguard configuration. That's nuts. With a diameter of 0.620", the SLIM series was designed so that shooters could permanently attach a muzzle device and still get their gas block and barrel nut over the device.