Thermophore arthritis heating pad for an intense, moist heat that is perfect for fast relief, choose thermophore. these are the best heating pads you can get on the market.this amazing, highly effective arthritis pad provides temporary pain relief for the back, arm or leg areas of the body. get intense moist heat without adding any water. when the heating pad is turned on, the pads produce their own moisture by using the humidity in the air. please note: this model features an automatic 20 minute therapeutic heat cycle time in place of the momentary switch. for more control over your heat therapy, please choose the thermophore automatic moist heating pad. the thermophore arthritis pad produces moist heat automatically. moisture is drawn from humidity in the air and retained in the outer fleece cover. the arthritis pad produces moisture for 20-30 minutes. after that time, the fleece begins to dry out and the unit should be set aside to regain moisture.