AR15/M4 steel Muzzle Brake with Crush Washer. The muzzle brake is a two chamber design with 14 CNC machined ports that direct the propellant gasses upwards and to the sides to reduce muzzle climb and felt recoil. No open ports on the bottom of the muzzle brake, to reduce dust signature when shooting prone.Features:AR15/M4 Muzzle Brake with Crush WasherMuzzle Brake adds 1.5"+ to the length of the barrel with the use of the crush washerOverall length: 2.14" Screws onto standard AR15/M4 " X 28 threaded barrels (with .223 5.56 bore)Muzzle Brake has two chambers with 14 ports that direct the exiting propellant gasses upwards and to both sides to reduce muzzle rise and felt recoilThere are no open ports on the bottom of the Muzzle Brakethis will reduce the dust signature when firing proneSteel Construction with Black Finish