Vector Optics Adjustable Gas Block Single 20mm Picatinny Rail Mounting .233 Rem LR-308 Barrel 0.75" Inside Diameter Aluminum

                    Vector Optics 0.75 Inch Adjustable Gas Block Mount (SCRA-35)      Low Profile, Designed for Real Fire Caliber, Full Metal      Model: SCRA-35 Install on 0.75 inch Barrel Top picatinny rail for addtional laser and flashlight quick-detach Diameter: 19mm (0.75 inch) Length: 47.5mm (1.87 inch) Height: 41mm (1.6 inch) Weight (net): 70g (2.8 ounce) Can use supplied hex hey fto adjus for release and fasten on the barrel High quality aluminum alloy in durable black matte finish Shock proof designed for real fire caliber           P.S.  Advertised item side hole fit standard 5/64" (0.078'') roll pin, if you request roll pin size for large hole gas tube. Pls leave a message to me