Built-in rechargeable Li-ion battery can be re-used approximate 500 times
Temperature switch has two modes "on/off". The first position is at about 39 degree, the second is about 43degree.
PET electric heat film generates heat fast.

It is more economical and environmental protection than the general warm pack
It can be charged by using the additional USB interface connected to the computer.
It adapts to global voltage 100V~240V
Piano paint, ethereal apprearance, portability.