This is our .308 barrel, gas block, and gas tube. This kit was put together for the smoothest shooting .308 barrel you will ever install on your AR-10.18" and 20" CHF Rifle Length BarrelFeatures: Chrome Lined Cold Hammer Forged 1/12 Twist Rate 5/8 X 24 Thread Pitch for Muzzle 7.62 Nato Chamber .750 Gas Block Seat M4 Style Ramped Barrel Extension MilSpec Phosphate Coating Heavy ProfileLow Profile Gas Block Solid Billet Steel .750 I.D. Black Nitride CoatingProprietary Length Tube Mil-Spec 304 stainless steel Black Nitride Finish Stainless Steel Spring Pin Weight: 3lb 2oz