BCM® Low Profile Gas Block for AR15, M16, M4, M4A1. Machined of steel, phosphate finish, for .625 barrels. Manufactured within very tight Mil-Spec tolerances on all ID's. Barrel ID honed after finish per USGI TDP. Made by Bravo Company MFG, Inc. with set screw mounting. Set Screws are Steel 10-32 x 3/16 Knurled Cup Point
