The LBE Unlimited low-profile gas block fits a .750-inch barrel journal and ships with a mid-length gas tube, so you have a matched block-and-tube set ready to install. The low profile lets the block sit cleanly under a free-float handguard. The block is steel with a nitride finish and the gas tube is 304 stainless steel. Features: Low-profile .750-inch gas block Includes a mid-length 304 stainless steel gas tube Steel block with nitride finish Set screws and gas-tube roll pin included Made in the USA Pair this with a .750-inch-journal barrel that uses a mid gas system. The gas-tube length must match your barrel's gas system length for proper function.