iPhone accessories company mophie has announced the worldwide availability of its Juice Pack Air product - a combination of case and external battery for the iPhone.

Mophie claims that it's the thinnest Apple-certified external battery available for the handset. It has a 1200 mAH battery integrated into an external hardshell. A pass-through design means that you can charge the battery and sync the iPhone at the same time.

The company reckons that you'll get 270 hours more standby time from the Juice Pack Air, or 4.5 hours of talk time or internet use. It's available now from Apple shops and Apple.co.uk, costs £70 and comes in black, white and purple.