This is a set of handwarmers that can also be used to recharge a phone or iPad. And as a bonus, it has a lighted makeup mirror. I primarily tested the handwarmer function and that works fine. The handwarmers do get nice and warm, which is pleasant, considering how cold it has been around here. My major complaint about them is they are huge compared to other handwarmers. They are much too big to fit inside a large mitten, so I carried them in my hands with gloves on while I was walking outside for about an hour.
The backup battery to recharge my phone may be a bonus for some, but I can't see taking this handwarmer on a trip where I would need that function. However, it does have all of the connectors you might need available: USB C, micro USB, Lightning and USB A.
I am giving this 5 stars because it does work well as a handwarmer and with the large size, it stays hot for quite a while. But I have to admit that if I were looking for a handwarmer, I would probably get something else that is a little smaller unless I really needed something that runs a long time.