These quality machined steel Gas Blocks are lightweight, strong and small enough to use with almost any handguard. They mount using two set screws on the bottom. If your barrel does not have corresponding “dimples” drilled in, or the slots from taper pins, some gun-smithing may be needed to ensure a secure attachment to the barrel. This gas block will fit on .750” diameter barrels. Black phosphate finished – made in the U.S.A.