Sometimes battery life isn't enough on the iPhone 5 - this is supposed to fix that. It does, it bulks up the phone by a large amount, and the iPhone doesn't exactly go in that easily, you kind of have to whack it in and then snap it - the battery life overall is good, I'd say it essentially doubles my battery life if I need to use it. The fact it's so bulky and thick is something you have to deal with, but for what it does? Perfect. Can charge the iPhone and the case at the same time, and it works as it should, but not perfect.