This is a high-performance replacement laptop battery for the Sony VGP-BPS21, guaranteed to meet or exceed the OEM specifications of your original. The laptop battery is 8.05 x 2.21 x 1.38 inches with an output of 10.8 volts. The chemistry is Li-Ion at 6600mAH capacity. Manufactured by Empire Scientific, model number LTLI-9159-6.6. 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.