You asked for it and TNTE delivers! This Pencil 11.5" barrel will be a great addition to your SBR and pistol stable. Featuring a 5.56 NATO chamber, the bore and chamber are chrome lined and the exterior has a phosphate coating. The barrel is made from 4150 11595E Steel. The gas system length is carbine. In being a retro barrel the gas block is .625" diameter.