KAK Industry Plan B A2 Flash Hider, 1/2X28 Thread Pitch, 223-9MM (.375 Bore), Plan B Compatible, Nitride Finish, Black 410-2103-003 Plan B muzzle devices feature a taper followed by threads, resulting in repeatable lockup and a proper seal between the muzzle device and suppressor adapter. These Plan B muzzle devices are compatible with Plan B suppressor hubs. It is recommended to use Rocksett for installation and 20-25 ft-lbs of torque. Some suppressor manufacturers will not honor warranty claims if other brands of muzzle devices are used with their suppressors.