This is a high-performance replacement laptop battery for the Acer Aspire 4820, guaranteed to meet or exceed the OEM specifications of your original. The laptop battery is 10.6 x 1.86 x 0.94 inches with an output of 10.8 volts. The chemistry is LI-ION at 4400mAH capacity. Manufactured by Empire Scientific, model number LTLI-9189-4.4. 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.