Electric heater with USB cable, it can be plugged in any power supplies with USB port, such as power bank(5V/2A is recommended), car charger, laptop, desktop computer, etc.
Electric heating will warm your wrist and enhance blood circulation reduce knee pain from the deep
3 levels adjustable temperature of 122℉/ 140℉ / 158 ℉, adjust according to your needs, safe to use, no worry it'll scald wrist
Portable and Convenient to use, you can use it at home, office, hotel, in the car when you are working, watching TV, reading, travel and driving.
Adjustble with hook and loop fastner, one size fit most men women and teenagers