1800 mAh Extended Slim Design Battery for HTC ACE, HTC Desire HD, HTC Inspire 4G, HTC Surround, BD26100 This is a High Quality Battery for the HTC Desire HD, Inspire 4G, HTC, HTC Surround, HTC Ace Capacity: 1800 mAh; (longer battery life compare to standard 1230 mAh battery) Same size as standard battery. Do NOT required to use bulky back cover. Please allow the battery to "break in" with fully charge and discharge 5 times to enjoy max charge capacity. Keep one as a spare and you like to use your Smart Phone for a longer period of time when you call, play games or while browsing.