Tiger Rock AR-15 223/5.56 Shark Muzzle Brake 1/2x28 Pitch Thread w/ Crush Washer. It has a total of 8 ports to redirect pressure resulting in less muzzle rise and overall recoil. Crush Washer not Included Specifications for Tiger Rock Shark Muzzle Brake: Manufacturer: Tiger Rock Threads per Inch: 1/2x28 Gun Make: AR Platform Gun Model: AR-15 Package Contents: Tiger Rock Shark Muzzle Brake What firearm models does the manufacturer say Tiger Rock Shark Muzzle Brake is compatible with? The manufacturer says that Tiger Rock Shark Muzzle Brake is compatible with AR-15Tiger Rock MBR25: AR-15 223/5.56 Shark Muzzle Brake 1/2x28 Pitch Thread w/ Crush Washer