This is a high-performance replacement laptop battery for the Sony VGN-AR520E, guaranteed to meet or exceed the OEM specifications of your original. The laptop battery is 8.13 x 2.65 x 0.78 inches with an output of 11.1 volts. The chemistry is Li-Ion at 6600mAH capacity. Manufactured by Empire Scientific, model number LTLI-9040-6.6. 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.