The MEGA GTR-3H Billet Upper Receiver comes stripped and ready for your next custom AR build. ZEV starts with high-quality 7075 T6 aluminum billet and machines them to exceed mil-spec dimensions and are held within A .001" tolerances, giving you maximum compatibility with mil-spec and aftermarket parts and accessories. The MEGA GTR-3H Billet Upper Receiver offers superb strength and versatility for building an AR-15 configured exactly the way you want it. FeaturesMachined from American Made 7075-T651 billet aluminumMachined to exceed Mil-Spec requirements, with critical tooling dimensions held within +/- .001"True Black Class 2 Type 3 Hard coat anodizeCompatible with all Mil-Spec parts kitsM4 feed ramps cut standard