I bought this ipad 2 battery pack for a trip to Japan, as my devices usually run out of power long before the end of the 12 hour flight. I was particularly attracted by the dual USB ports which allow you to charge two devices simultaneously, and the large 5000mAh capacity. It turned out to be invaluable and an essential item for people who travel with lots of gadgets. For our trip my wife and I between us had and iPhone 3G, iPhone 4, ipad 2,Sony PSP Go, Nintendo DS and two Ipods and we got all the way there with all devices still running and some power still left in the pack. I was able to play the PSP for at least twice as long as would have been possible without it and could have played even longer (theoretically it could give you probably 4-5 times more play time in addition to the standard battery). It has huge capacity and will charge a 3G iphone several times easily, the iPhone 4 seems to suck more juice out of it, so possibly only two charges for that.