Although the iPhone 4's battery life is better than that of previous Apple handsets, Web browsing and using GPS, for example, will still wear it down quickly. If Mophie's claims about battery life are valid -- and we found they pretty much were with the Juice Pack Air for the iPhone 3G -- you should be able to eke out just under 12 hours of Internet browsing over 3G, as opposed to 6 hours without the battery pack. Similarly, using the Juice Pack Air should enable 20 hours of video playback, rather than 10, and 80 hours of audio playback, rather than 40.
The case will also afford your fragile iPhone 4 some much-needed protection, and could solve the pesky reception problems that blighted the device at launch.
The case has four LED lights that indicate battery status. It has a rubberised finish that's soft to the touch, and a silver band around the edges, mirroring the iPhone 4's silver streak. Apparently, it also redirects sound from the bottom of the phone to the front, for improved audio.
Currently, you can only get the Juice Pack Air for the iPhone 4 online from the US. It costs $79 (£52) on Mophie's site, but you'll have to factor in shipping charges as well -- or you'll have to wait until the case rears its head this side of the pond.
Let us know what you think of the Juice Pack Air in the comments section below. Have you used one before? If so, was it any cop? Or would you advise people to avoid it in the same fashion as they would a nasty case of wet leprosy?