MiLi’s PowerSpring 4 Extended Battery does not only keep you connected longer, but also protects your iPhone 4. From MiLi comes the world’s thinnest iPhone 4 battery pack and charger that will double your battery’s life. You can now get rid of bulky accessories and make your iPhone 4 fit in your pocket. Love and enjoy MiLi’s PowerSpring 4 Extended Battery’s sleek form and fitting design.