Rugged Suppressors Muzzle Brake, 3 Ports, 1/2X28 MB011 3 Port Brake featuring our Dual Taper Locking System(TM)" compatible with our Radiant762" Surge 7.62" Razor 7.62 and Micro30.This muzzle device is designed for reducing recoil when shooting unsuppressed. The 3 Port Brake has a .30 cal aperture" but the 1/2x28 variation can be permanently attached to 5.56 14.5" barrels in order to meet 16" requirements.