Not sure about the qualify of Mophie any longer. I bought two of these - one refused to charge when left on a charger overnight (blinking lights but no indication of charge). Too bad because I'd enjoyed using Mophie products in the past but I will be switching when I purchase my next extended battery because I no longer trust their quality.
I purchased this to extend my time on my 3rd gen ipad.
When my ipad got to 5% of battery life remaining, I plugged it in and only got an additional 2:23 of life, until auto shutdown turned off my ipad, and that was with the screen brightness reduced to 50%.
Additionally, If your ipad battery fully discharges and automatically shut itself down, it takes about 6 minutes after plugging in the juice pack before you can get it to turn back on.
As someone else mentioned..... its ok if you know its limitations, but don't expect too much from it.