The Spyder Digital PowerShadow i4 Battery Case & Charge/Sync Dock i4 is not just another battery add-on. It has built-in smart technology that intelligently augments your iPhones' power for maximum performance and reliability. For example, you can charge and sync without removing your iPhone from the i4 case. A variety of flexible charging/syncing options offer unsurpassed convenience, flexibility and ease of use. It has lightweight, ultra-slim polycarbonate body, with its satin rubber finish, feels ruggedly luxurious in your hand; and easily slides into your pocket.