Something of a jack of all trades, the main attraction of the SLXtreme is that it features a built-in solar battery. This means that, in theory, if you live somewhere sunny enough, your iPhone would never need a charge. Wishful thinking perhaps, but it’s still a great feature to have. It also waterproofs your phone and is totally shock and drop-proof. Price: £94 • You may also like the latest impossibly slim waterproof sony xperia z3 compact android tablet.