A Power Bank is an essential item these days to keep your iPhone or Android charged. I use my iPhone for navigation, route mapping, photography, videos, social media etc so it's on all the time draining the battery. A big Power Bank should keep you in power all day with a full charge over night. I don't normally go for gimmicks but this one has a torch which is useful and solar charging. Solar charging is usually a bit disappointing at the moment but a trickle charge when you are riding or walking helps top it up. If you end up in an emergency situation the solar might just help!