Amazon.com: Sunbeam USB Heating Pad for Back, Shoulder, Arm, and Leg Pain Relief with Power Bank Pocket and Auto Shut Off, 12.5 x 7.5″, Grey : Health & Household $12.24

It’s a good heating pad for on the go. It heats up nicely, but the velcro does not have a strong hold. I added another inch of velcro, and it is all good to go now. Needs a usb battery pack or needs to be plugged into a 2A usb port. 50% off right now.
https://www.amazon.com/dp/B08RMN5KZX