After charging the powebank from my mains twice, I have found this item to be only capable of charging my nexus 7 ONCE and a bit (15%) from empty OR my nexus 4 about 4 times from a 50% charge on the phone.
Not what I was lead to believe from previous reviews.
Item is adequate for top up use ONLY.
Do not make the mistake of thinking that this unit will be sufficient for a tablet and phone combination for a weeks camping holiday because it will let you down.
Dont know why some of these reviews are so over the top, there is NO WAY any charger will charge a flat Iphone 4 in 20 mins!
Ye cannae change the laws o' physics captain!