I just started playing Ingress on my iPhone (my very first gaming geek experience) and a friend recommended the Anker for more power. I've had a lot of external battery packs and they've all conked out. This one is industrial strength and - apparently - what all the super hard core geeked out Ingress players use to extend their phones life, so I'm into it. In it's own words: "Monster capacity (15000mAh) charges the iPhone almost 7 times." What more can you say?