With the iPhone, the problem is its autonomy. When hiking, it's barely a day. With this battery shell, I can continue my walks with GPS coordinates regardless of battery. Charges via micro USB. Please note this-said, two small flaws: - Once on the sector, the phone is charging the battery THEN. annoying because the phone is discharging while the battery is charging. - My iPhone loses some of its ergonomics and its finesse. But we have something for nothing.