It also has its own 30-pin connector so you can sync your phone while it's in the case, a feature that other similar cases don't have. The case charges via USB, and there's an LED indicator showing you how much power remains in the lithium polymer battery.
Last month when I headed to Chicago's Lollapalooza music festival, I wouldn't have made it through without my Mophie Juice Pack Air. Part case and part external battery, the Mophie kept my iPhone charged and ready to go through the entire festival day, even though it was in near-constant use. And now, there's a Mophie Juice Pack Air for iPhone 4 users, too!
Check out the Mophie's specs after the jump.
The days are long, and there was a lot of texting and social networking, but the Juice Pack pulled through! Read all the reasons I'd recommend this device— and one reason I wouldn't — after the break.