1/2"-28 Thread. The popular Phantom Flash Suppressor has been redesigned to work as a muzzle compensator while maintaining the excellent flash hiding capabilities of its predecessor. This 5 port design has no downward facing port which helps eliminate dust problems when shooting in the prone position. The Phantom Suppressor keeps the aggressive front end used in hand to hand situations. For threaded barrels only. Includes crush washer. Made in the USA. YHM