This is a high-performance replacement laptop battery for the Compaq Presario CQ40-305AU, guaranteed to meet or exceed the OEM specifications of your original. The laptop battery is 8.6 x 2.38 x 1.68 inches with an output of 10.8 volts. The chemistry is Li-Ion at 8800mAH capacity. Manufactured by Empire Scientific, model number LTLI-9132-8.8. 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.