The Breek Arms Plan B Echo is a single-port muzzle brake for .30 caliber barrels threaded 5/8x24. It redirects propellant gas to counter recoil and muzzle rise, so your sights settle back on target faster for flatter follow-up shots. 5/8x24 is the common thread pitch on .308 Win / 7.62x51 rifles and many other .30 caliber barrels. The single-port layout keeps the brake simple and compact on the end of the barrel. Features: Single-port muzzle brake design Sized for .30 caliber bores 5/8x24 threads Reduces felt recoil and muzzle climb Before you install: confirm your barrel is .30 caliber and threaded 5/8x24. Do not mount a .30 caliber brake on a larger-bore barrel. Use a crush washer or shims to time the port correctly, and check bore alignment before firing. Muzzle brakes are loud, and much of the blast is directed to the sides. Wear hearing protection and be mindful of anyone on the line next to you.