This is a high-performance replacement digital battery for the Nikon D2100, guaranteed to meet or exceed the OEM specifications of your original. The digital battery is 2.04 x 1.45 x 0.55 inches with an output of 7.4 volts. The chemistry is LI-ION at 1000mAH capacity. Manufactured by Empire Scientific, model number BLI-401. We offer a 1 Year Warranty with purchase. See this product elsewhere at a lower price? Call or email us; we have a Price Match Guarantee.