POF USA Phoenix Muzzle Break Double Port w/ Lock Nut 9mm 1/2x28 Black. It helps control muzzle impulse for ultimate accuracy and an unbelievably soft recoil. Comes complete with a nitride heat treated collar and 5 strike prongs. Specifications for POF USA Phoenix Muzzle Brake: Manufacturer: POF USA Color: Black Projectile Caliber: .355 Caliber Caliber: 9mm Luger Finish: Anodized Fabric/Material: Steel Threads per Inch: 1/2x28 Gun Make: AR Platform Inner Diameter: 0.3 in Length: 3 in Weight: 6 oz Condition: New Features of POF USA Phoenix Muzzle Brake Nitride heat treated Double port muzzle break Package Contents: POF USA Phoenix Muzzle Brake POF USA 1865: Phoenix Muzzle Break Double Port w/ Lock Nut 9mm 1/2x28 Black