Super Duty MOD1 Complete Upper 5.56x45 NATO The Geissele Super Duty MOD1 Upper (Complete) features the latest in weapon technology available exclusively from Geissele Automatics. This complete upper chambered in 5.56mm features a nanoweapon-coated HUXWRX Flash Hider-QD muzzle device mounted to a Manganese Phosphate coated, CHF, Chrome Lined 1-7 twist barrel. Geissele barrels are precision machined and cold hammer forged utilizing the highest quality materials at their state of the art facility in North Wales, PA. The carbine length gas tube and Geissele Super Compact Gas Block with bomb-proof installation ensures reliability and optimal performance in extreme conditions. Include Mfg: Geissele Automatics