Geissele Super Duty Mod1 Complete Upper 12.5in 5.56MM Black. Foundational to the renowned quality and performance of this Super Duty system is the in-house produced Cold Hammer Forged chrome-lined barrel and Nanoweapon-coated Reliability Enhanced Bolt Carrier Group. Both the Geissele CHF barrel and Forged Stressproof Bolt are High-Pressure Tested (HPT) and Magnetic Particle Inspected (MPI) and work in concert to achieve unmatched dependability with match-grade accuracy. The Super Duty features a precisely balanced gas system including the bomb-proofed Super Gas Block and fine-tuned gas port sizing especially when combined with the Geissele Super 42 braided buffer spring (sold separately). These purposefully selected components minimize felt recoil while maintaining reliable cycling even in adverse conditions. The MOD1 features the signature Nanocoated HUXWRX Flash Hider-QD muzzle device offering seamless compatibility with the innovative HUXWRX FLOW series. Rounding out the MOD1 complete upper receiver group the well-vetted center-tab mated MK16 rail features stainless steel QD inserts to reinforce sling attachment. The Airborne Charging Handle provides ambidextrous use and accessibility and while maintaining a lower profile to eliminate snagging on gear. Manufactured with confidence and without compromise the Super Duty MOD1 adds value to the platform while continuing the reputation for excellence. Specifications for Geissele Super Duty Mod1 5.56mm 12.5 inch Complete Upper: Manufacturer: Geissele Caliber: 5.56mm Overall Length: 21.5 in Barrel Length: 12.5 in Barrel Profile: Tapered Gas System Length: Carbine Length Barrel Twist Rate: 1-7 Threads per Inch: 1/2x28 Muzzle Device: Nanoweapon-coated HUXWRX Flash Hider- QD 556 Finish: Type 3 Hardcoat Anodize Fabric/Material: Aluminum & Steel Handguard Length: 11.5 in Bolt Carrier Group Included: MIL-SPEC Charging Handle Included: MIL-SPEC Magazine Included: No Package Contents: Geissele Super Duty Mod1 12.5in Complete Upper Geissele 08-545B: Super Duty Mod1 Complete Upper 12.5in 5.56MM Black