SLR SR22 Muzzle Brake 5.56 1/2x28 Thread Black. 1/2x28 threading. Only .7 inches added to barrel length. Awesome performance in a small package stops muzzle rise completely. Proper port and bore size for maximum effectiveness. 1.36 inch Length. .92 inch Width. Included Accessories: Crush Washer Specifications for SLR SR22 5.56 Muzzle Brake 1/2x28 Thread: Manufacturer: SLR Caliber: 5.56x45mm NATO Threads per Inch: 1/2x28 Features of SLR SR22 5.56 Muzzle Brake 1/2x28 Thread: Single Port Brake . 1/2x28 threading. Only .7 inches added to barrel length. Awesome performance in a small package stops muzzle rise completely. Proper port and bore size for maximum effectiveness. 1.36 inch Length. .92 inch Width. Included Accessories: Crush Washer Package Contents: SLR SR22 5.56 Muzzle Brake 1/2x28 Thread SLR MD-SR22: SR22 Muzzle Brake 5.56 1/2x28 Thread Black