This is a high-performance replacement digital battery for the Casio NP20, guaranteed to meet or exceed the OEM specifications of your original. The digital battery is 2 x 1.28 x 0.18 inches with an output of 3.7 volts. The chemistry is Li-Ion at 650mAH capacity. Manufactured by Empire Scientific, model number BLI-216. 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.