This is a high-performance replacement laptop battery for the Apple MB771LL/A, guaranteed to meet or exceed the OEM specifications of your original. The laptop battery is 8.24 x 3.09 x 0.43 inches with an output of 10.8 volts. The chemistry is LI-POL at 4200mAH capacity. Manufactured by Empire Scientific, model number LTLP-9137-4.2. 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.