This is a high-performance mobile battery pack for the ULTRAFIRE WF-137, guaranteed to meet or exceed the OEM specifications of your original. The mobile battery pack is 4.75 x 1.5 x 1.12 inches. Manufactured by Empire Scientific, model number FBC-WF-137. 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.