The Nikon MS-D12EN Li-ion Rechargeable Battery Holder for MB-D12 Battery Pack allows users of the Nikon D800, D800E, and D810 digital cameras with the MB-D12 Multi-Power Battery Pack to use an EN-EL15 rechargeable li-ion battery instead of 8 AA batteries. Also, you can keep an additional MS-D12EN battery holder pre-loaded, so that you can quickly swap out battery sets.
