Mophie's Juice Pack Reserve External Battery is for those days that never end, those days when eight hours of talking or nine hours of video just isn't enough. Recharge your iPhone or iPod on a long flight, overtime at the office, or night classes that go on forever. It's slim, lightweight design allows you to take it with you on your key chain wherever your day takes you. Connect it directly to your computer or other USB charging port at night and you'll have two batteries when you walk out the door in the morning. Forget the daily outlet search and just charge your device wherever you happen to be when that red light goes on.