The integrated USB ribbon cable of this battery case serves to charge the iPhone 4, and also allows you for data transfer right in the case. There is a button that displays the phone's current level of charge. There is also a microUSB port on the left side of the aiPower i616. At 125.8 x 62.6 x 17.25mm, this battery case is compact. As an iPhone 4 case, the aiPower i616 offers temperature protection. The Aigo aiPower i616 has an output voltage of DC5V 0.5A.