Nearly twice the size of most standard heating pads. Providing 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. Original Thermophore Automatic Moist Heat Pack is designed with a special hand-held 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 as a safety feature.