Designed by a chiropractor, allowing for full coverage of the back, spine, lumbar area, arms, legs, hands knees and elbows to relieve back tension and aches. The heat lasts 60-70 minutes so you can fall asleep and not be harmed. To use as a cold pack, simply place in the refrigerator until you get your desired temperature. You will wake up in the morning feeling alive, rejuvenated, energized and focused.