The Geissele Super Duty MOD1 Upper (Complete) features the latest in weapon technology available exclusively from Geissele Automatics. This 11.5'' complete upper chambered in 5.56mm features a nanoweapon-coated HUXWRX Flash Hider-QD muzzle device mounted to an 11.5'' Manganese Phosphate coated, CHF, Chrome Lined 1-7 twist barrel. The carbine length gas tube and Geissele Super Compact Gas Block with bomb-proof installation ensures reliability and optimal performance in extreme conditions. Included is a brand new, 10.5'' Super Modular Rail MK16 that mates to the upper via a center aligning tab removing any chance of rail rotation. This rail is a variant of the 13.5'' SMR MK16, currently fielded by USASOC and renowned by operators for their performance and comfort. Also included is the Geissele Reliability Enhanced Bolt Carrier Group. This Nanoweapon coated BCG features a properly torqued and staked, chrome lined gas key. The Cam Pin is machined from advanced, medical steel known as H13 which is also coated with Nanoweapon for maximum corrosion and wear resistance. The Geissele Reliability Enhanced Bolt Carrier Group also features extended upper rails, providing greater stability and dramatically increasing feeding reliability. The Geissele Reliability Enhanced Bolt Carrier Group comes with the Geissele Stressproof Bolt. Made from Carpenter 158+, directly developed with Carpenter Steel metallurgists to create a material that is cleaner and has less impurities. This makes the Stressproof bolt stronger and more fatigue resistant. The Geissele Stressproof bolt is also forged, not machined from barstock. This optimizes the grain structure of the steel to yield a bolt capable of 5 times the life of a mil-spec bolt. Each bolt is rigorously inspected, high pressure tested, mag particle inspected and Nanoweapon coated. All of these technologies and advancements combine to bring to market a true next-gen upper for the AR-15 platform. The Super Duty Complete Upper from Geissele Automatics offers unmatched performance, accuracy and reliability.