Own the world's most effective flash hider. The proprietary features eliminate muzzle flash, even on CQB-length barrels. The BLACKOUT is inherently stronger and more impact resistant than four prong designs, while not being subject to the rapid erosion of closed-ended units. A high strength corrosion-resistant aerospace alloy, and ultra-hard Nitride finish provide the highest level of durability. Military tested and selected. This is the non-mount version for use without a silencer, in Fast-Attach for 9MM HK MP5-style 3-Lug Barrels! Torque wrench is need for installation - approximately 20-30ft.-lbs.