Quite decent quality and delivered quickly, there are three levels of heat adjustment separately for zones, back, stomach, chest, and neck. Size 4X for my height 172 and weight 95, a bit too big, it would be better if it was a bit smaller, but smaller is still okay. With a better fit, there is improved thermal efficiency. Maximum consumption, 2.2 A at 5V. So the power bank needs to have a capacity of at least 15 watts. The photo shows consumption at maximum, medium, and minimum power of all heaters. From the shortcomings: 1. there is no switch, only unplug from the power bank 2. It's inconvenient to live off the power strip, only through an extension cord if it doesn't cut off the power.