This 18" A4 MK-12 Profile Upper Assembly is designed for the shooter who plans to add a scope or optic, or already owns an A4 Carry Handle. It is a complete Upper Receiver Assembly - ready to snap onto your Lower. The barrel QPQ finish and machined from 4150 Chrome Moly Vanadium 11595E steel, rifled 1 x 7" RHT. An A2 Flash Suppressor, standard A2 F-Marked Front Sight base with sling swivel and bayonet lug are fitted. The assembly includes Knights Armament M5 Rifle Length RAS System Handguard - 1913 Spec Picatinny Rails.