The Low Profile Gas Block from BCM features a black phosphate finish and steel construction. Manufactured within very tight Mil-Spec tolerances, this block is designed for use with .75 barrels.Specifications and Features: Bravo Company Manufacturing BCM-LGB-750 BCM Low Profile Gas Block Manufactured within very tight Mil-Spec tolerances on all Inside diameters Barrel inner diameter honed after finish per USGI TDP Made by Bravo Company MFG Set Screw Mounting Set Screws 10-32x 3/16 Knurled Cup Point Machined steel Phosphate Black Matte Black