Until quite recently, I had only heard of Power Pack's but didn't know anything about them. However because I favoured buying a longer power charge cable than that which is issued, I did some research and found that for the same price (or thereabouts), a power pack might prove to be more useful, so I bought one. The model is not much larger than my phone. The idea is that you charge it up, then somehow, it holds the power which when your ipad requires charging and you're away from a power source, you simply connect the two together and the pack transfers to the ipad. With the Power Pack, comes a connector which has about 7/8 different plugs, so you know that there will be one which will connect to your ipad/tablet or phone. Two strengths of power are "ejected" for want of a better word. To compliment my pack, I have bought a soft cushioned camera case for a £1, so when it is in my rucksack or whatever, at least it is protected. These items can be bought for a wide range of prices, mine cost about £30. If you have one, I'd be interested to hear if you have found it useful, or if it';s one of those gadget things that doesn't see the light of day.