It's the standard battery for the iphone. These guys can't even make a 10 minutes phone call without flat battery.
Seriously. I think it's ridiculous this kind of devices are needed at all. 5 - 7 days days of normal use should be the standard for EVERY mobile.
On top of that, wireless charging the standard for every new device in the market. And where are creative solutions? Why for example do notebooks not have a area where we place our phones for wireless charging? Answer: They want to sell us expensive gatchets.