Knight's Armament MK12 Mod 1 Low-Profile Gas Block fits inside the Free-Float RAS's allowing the RAS to extend past the standard front sight. I.D. is 0.750 inches. Attaches with two set screws, provided. This is the gas block used on the original MK12 Mod 1 guns.
*Note: Gas tube roll pin sold separately, uses standard gas tube roll pins.