Whether your mp3s are running it down while you run on the treadmill, or dozens of rounds of Angry Birds Space is making your battery angry at you, everyone could stand to squeeze more time out of their cell phone battery. Now the Mophie Juice Pack Air helps you do it. The Mophie Juice Pack Air is a phone case for the iPhone 4/4s that recharges your battery while it holds it, giving you longer life for all your iPhone uses.