You can find the Battle Arms Development Thumper Muzzle Break .223/5.56 Black here. Fast $9.95 shipping! Orders over $200 ship for free!
The Battle Arms Development Thumper Muzzle Break was designed to reduce recoil and muzzle rise to keep you on target. Made from 17-4 Stainless Steel and has a black nitride finish. Does not include a crush washer.
Caliber: .223/5.56
Threads: 1/2X28 TPI