Announced in January, Incipio's long-awaited iPhone 5 version of offGRID Pro ($100) has finally arrived 11 months later for testing. Based upon the excellent iPhone 4/4S version of offGRID Pro, this jet black battery case delivers unparalleled power for the price point -- 4000mAh spread across two included 2000mAh rechargeable batteries that can be swapped on the road as needed, keeping the size of the case highly competitive with rival options.…