Onite&reg; Blackberry Curve 8520 8530 Black Battery Door With 2400 mAh battery High Capacity rechargeable battery rated at 1800 mAh for your cell phone Expect to Approx. Double Your Talk and Standby Times Extended battery for you to keep as a reliable extra power source handy Advanced technology keeps phone working at optimum performance. Includes a battery cover that is specifically designed for the battery and your phone