Get on-the-go power for the iPhone 4 in a light-weight and ultra-thin external rechargeable battery case. The mophie juice pack air is designed to virtually double the time you have to Rock, Talk, Surf and Send with your iPhone 4! The juice pack air is a rechargeable external battery concealed inside of a protective form-fitting case for the iPhone 4. It offers you the full protection of a hard-shell case while providing virtually twice the battery life of the iPhone alone; all in an ultra-thin, light-weight, low-profile design. Check out below what makes the new juice pack air so cool!