The AAC 556-SD rapid attach silencer/flash hider is suitable with barrels that have a thread pattern of 1/228 TPI (threads per inch). It is made of stainless steel and has a black oxide finish. The AAC 556-SD Fast Attach Silencer Flash Hider is easily removed for cleaning or storage thanks to the supplied jam nut, which also secures it to the muzzle of your handgun.