OLD STYLE RECOIL COMPENSATOR Muzzle Brake with Lock Collar JAM NUT fits MAC 10 45 acp or any weapon with 7/8x9 tpi threaded barrel ..Compensator screws right onto your MAC 10 45 semi or subgun with threaded barrel and locks in place with lock collar jam nut. Made of steel construction and is original Cobray design..Condition is BRAND NEW and has Black finish. Provides your MAC with recoil control for better accuracy and control during fire as well as a MODERN Hi-Tech look and thread protection.