Combining a stylish and protective case with a portable battery booster, Mophie’s Juice Pack Air is available for a variety of Apple’s smartphones, including the 3GS and iPhone 4.

Price: £89.99 | Mophie

As well as protecting the Apple handset against knocks and scrapes through its rugged yet form fitting shell Mophie’s Juice Pack Air boasts a rechargeable external battery that all but doubles the iPhone’s staying power.

Providing the smartphone with 6 hours of talk time over a 3G network and 12 hours on a 2G service, the Mophie Juice Pack Air also offers up to 36 hours of additional audio playback and up to 9 hours of video playback whilst away from a mains power source.

Finally it improves audio output - making this far more than another iPhone case.