You know how it goes: You're waiting all day for that important call when the battery dies... Not today! We’ve teamed up with Blue Bud to offer you an iPhone 4 charging battery case, for just £12.99. That’s a huge 63% off the usual price of £34.99. Simply flip the on/off switch to toggle charging. It’s that simple. The case will provide a constant trickle charge to keep your iPhone battery indicator on full for longer. You charge the case in the same way that you would charge your phone. The case boasts a hefty battery which should give your phone an extra 6 hours of talk time or 5 days on standby. Here are the specs:

• 1900 mAh Li-polymer Cell Extended battery pack
• Four LEDs on the case to tell you how much battery is left.
• Non-slip rubber that eliminates iPhone 4 signal interference.
• Push-up to open: case slides open to allow you to take better photos.

Redemption is easy: once the deal ends we’ll send you a unique wowcher code. Just head over to Blue Bud online to complete your purchase.