Hold button down to start moist heat. Let go and it turns off. Finally, a product that provides an area of heat therapy large enough to cover the entire spinal area, the length of a hip and leg or all across both shoulders, to effectively relieve pain and relax all the associated muscles – not just one small, isolated point. Thermophore Classic Plus Petite Heat Pack is designed with our Classic Easy-Comfort™ Switch. Just press for heat, release to cool and alternate as often as you like. If you happen to doze off and your hand relaxes, the unit will cool down as a safety feature.