All iPhone 4 owners know what it’s like. You’re in the middle of reading messages from your friends, posting updates, watching videos or something else entirely when your iPhone runs out of juice! The Sandberg BatteryCase for iPhone 4 extends battery life considerably. The battery fits the back of your iPhone, like a standard protective cover, and you can charge your iPhone without any fuss. The BatteryCase can easily be charged via a USB port.