This is a high-performance replacement cellular battery for the Nokia BL4B, guaranteed to meet or exceed the OEM specifications of your original. The cellular battery is 1.8 x 1.34 x 0.18 inches with an output of 3.7 volts. The chemistry is Li-Ion at 600mAH capacity. Manufactured by Empire Scientific, model number BLI-973-.6. 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.