This is the Piercision Rifles 1/2x28 brake. This is a great streamlined brake for the sporter contours out there. The ports on it are all 90 degrees which redirects the gas blast/concussion away from the shooter. Very effective brake for its size. Great for sporter contours with big enough muzzles for a 1/2x28 thread.
The O.D is .770".
This brake works great for barrels with a muzzle diameter of .560"-.620"