Another clever idea from Etón for when you need power on the move with your iPhone, the Mobius rechargeable battery case provides extra talk time from its own power or the sun.

Designed for the iPhone 4 and 4s and Appleapproved, it features a solar panel that needs only one hour in the sun to provide an extra 25 minutes of talk time, 20 minutes of internet use, 35 minutes of video playback or over two hours of audio playback.

Mobius features a quick charge time, the highefficiency monocrystal solar panel recharging the 1800mAh lithium ion battery pack on the back of the case. It also has optional charging via computer using a micro-USB cable.

Once the battery has been charged, a standby switch can turn off direct power transfer to the iPhone, allowing the case to charge and store energy in its own battery – only using the power when it is needed.

Weighing just 3.4 ounces, the case has both a battery charge and solar charge indicator and snaps onto the back of the iPhone.

Mobius retails for £69.99 and is available from are available from Amazon and other retailers. Click here to buy from Amazon UK