The ZEV Muzzle Device was designed to provide the dual benefit of flash suppression and muzzle rise reduction. The shoulder of the muzzle device extends over the barrel to cover the included crush washer and provide a uniform appearance. Wrench flats are incorporated for ease of installation. – The ZEV Muzzle Device is only compatible with barrels that have a .750 or smaller gas block journal due to the fact that the body of the muzzle device extends over the shoulder of the barrel. – Provides flash suppression and muzzle rise reduction – Crush Washer included