This is a high-performance replacement cellular battery for the ZTE Z221, guaranteed to meet or exceed the OEM specifications of your original. The cellular battery is 1.82 x 1.4 x 0.226 inches with an output of 3.7 volts. The chemistry is LI-ION at 920mAH capacity. Manufactured by Empire Scientific, model number BLI-1355-.9. 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.