This complete Windham Weaponry 18″ Fluted .308 Barreled Upper Assembly includes a CNC machined 7075T6 aircraft aluminum flat top Upper Receiver with Bolt Carrier Assembly, Charging Handle, Forward Assist, and Ejection Port Cover. The barrel is a highly accurate, 18” medium profile fluted turning – chrome lined and machined from 4150 Chrome Moly Vanadium steel. It is rifled 1 x 10” Right Hand twist and includes an A2 birdcage type Flash Suppressor. A railed gas block with sling swivel and bayonet lug allows the attachment of a variety of accessory front sights. Two piece aluminum heat shielded handguards complete the barrel. Steel parts are manganese black phosphate finished, and the aluminum upper is finished in Mil Spec black hard anodize for a non-reflective matte surface and protection against corrosion.