Also available with free click and collect from the Maplin website. http://www.maplin.co.uk/p/iwalk-chameleon-battery-pack-for-iphone-5-and-5s-white-n05dt
Not suitable for everyone, As its iPhone. Though if you're still using the 5, 5s or SE, this is great if your battery doesn't last as long as you'd like, or when travelling.
iWALK Chameleon Battery Pack For iPhone 5 5s White Case Charger 1900mAh Protect
1900mAh capacity lithium-ion rechargeable battery
Compatible with iPhone 5 and 5s
Officially certified by Apple
One-piece protective case with a shockproof, sleek and slim design
Simultaneously charge your iPhone and Chameleon chargerThe iPhone 5 / 5S Power Case is equipped with a 1900mAh lithium polymer battery to fully charge your iPhone 5 / 5S and provide up to 9 hours of additional talk time. The LED battery indicator shows charge and discharge status, and the sleek design and easy-grip exterior give it a great feel. Its ON / OFF switch preserves power and allows you to keep the case on your phone when not in use. You'll also have full access to all controls and ports. The earphone jack port provides complete access even for L-shaped plugs. Pass-through technology allows you to charge your power case and iPhone 5 / 5S at the same time. You can even sync to iTunes through this power case, using the supplied Micro USB cable.