Oooh this is such a good idea!
It’s both a hand warmer and a power bank, plus a flashlight!
One time I was in a city outside all day in the freezing cold and handwarmers saved the day. I just kept movign them from pocket to pocket and they made a huge difference.
Plus people like my DD get freezing cold hands, and I think she would like this.
I bought the bronze:

(First post Above is the black)