If you want the versatility of a standard 3/4x10 9mm thread and also want a 1/2x28 thread, then this is the barrel for you. It offers machined 1/2x28 threads on a standard 9mm barrel so you can thread on suppressors and muzzle brakes. It is a new barrel with both threads. (Upper sold separately) Fits M-11 SMG, Semi Auto and MPA mid sized 9mm. Does not fit MPA Mini 930.