Fits 9mm rifles and other rifles up to .358 diameter bullets with thread pitch of 1/2-28. Three large baffles with six side ports and no top vents direct muzzle gases to the side, away from the shooter. Effectively counters muzzle rise and recoil, minimizes felt muzzle blast. Made of 4140 steel with a black nitride finish, measures .920” diameter and 2" length. Weight including lock nut is 3.5 ounces. Solid bottom minimizes dust printing when shooting prone. Easy installation, secured with the supplied lock-nut.