Kexuan 1/2x28 Competition Grade Muzzle Brake for AR-15 Steel with Black Phosphate Finish. Crush washer and Jam nut included. High quality steel construction with Phosphate finish and CNC machined tech Specifications for Kexuan AR-15 Competition Grade Muzzle Brake: Manufacturer: Kexuan Color: Black Caliber: 5.56x45mm NATO .223 Remington Finish: Black Phosphate Fabric/Material: Stainless Steel Threads per Inch: 1/2x28 Gun Make: AR Platform Gun Model: AR-15 Package Contents: Kexuan AR-15 Competition Grade Muzzle Brake Jam nut Crush washer What firearm models does the manufacturer say Kexuan AR-15 Competition Grade Muzzle Brake is compatible with? The manufacturer says that Kexuan AR-15 Competition Grade Muzzle Brake is compatible with AR-15Kexuan MZ-07-01-B: 1/2x28 Competition Grade Muzzle Brake for AR-15 Steel with Black Phosphate Finish