The Ballistic Advantage® Premium AR-15 Mid-Length 223 Wylde 1:8 Stainless Steel Barrel w/ Lo Pro Gas Block features a 1.03" gas block seat for .750" low profile gas blocks ONLY. This drop-in barrel features a Hanson profile and is constructed from hardened 416R stainless steel with a corrosion-resistant bead blasted finish. This barrel boasts a 1:8 twist rate and is compatible with mid-length gas systems. The 1/2x28 thread pitch is perfect for your favorite muzzle devices. HP and MPI tested barrel. Features nickel boron coated extended M4 feed ramp extension and comes with Lo Pro gas block.