Aigo aiPower i616 USB Battery Case is the new solution to add more power to your iPhone 4. It has a thin dimension that won’t add much weight and thickness to your iPhone 4, so you won’t have any problem bringing your iPhone around. However, you can’t equipped your iPhone 4 with any case that you may have because it won’t fit into the Aigo aiPower i616 USB battery case.
Aigo aiPower i616 USB Battery case has a hidden USB connector that you can flipped out to charge the battery. So when the juice run out, you can simply reveal the connector and hooked up with USB port. If you think the connector head is too short, there is also a secondary microUSB port that you can use on a longer USB cable if necessary.
Aigo aiPower i616 USB Battery case is available for $80 directly on Aigo.