Nikon EN-EL4a Rechargeable Li-Ion Battery for MB-D10 Battery Pack and Nikon D2 and D3 Digital SLR Cameras (Retail Packaging). Power your Nikon D2H, D2Hs, D2Xs, and D3 digital cameras without relying on disposable batteries with the high-capacity Nikon EN-EL4a rechargeable lithium-ion battery. Also compatible with the optional BL-3 battery chamber--which supports the MD-D10 grip for the D300 and D700 cameras--the battery employs lithium technology to ensure a maximum battery life and maximum power. Plus, the battery doesn't suffer from a memory effect, so you can recharge partially drained batteries without reducing performance. Specifications include an output voltage of 11.1 volts, a capacity of 2,500 mAh, and dimensions of 3.2 by 1 by 2.2 inches (W x H x D).