If you want to add a tactical finish to your AR15, then this is for you! It is an AR flash hider/muzzle brake bored out to fit a 9mm round. Since typical AR muzzle brakes are designed only to fit a .223 round, this is machined to fit a 9mm round. This increases muzzle control and helps to reduce recoil. Threaded in 1/2" x 28 threads. Also fits MPOA Mini, MPA 16" barreled carbine uppers, MPA20SST-A, & MPA20T-A & others with a 1/2x28 thread.