Just Posted: Our review of the Pixel Vertax D12 third-party battery grip for the Nikon D800. Third-party manufacturers offer a broad range of accessories for popular cameras, providing more options or lower prices. Vertical grips can aid the handling of DSLRs for portrait-format shooting and when working with long, heavy lenses. In this short review, we look at the Pixel Vertax D12 battery grip. At $99 it's considerably cheaper than Nikon's MB-D12 but can it do the same job? Click through for our opinion.