Clix Therapy Hot & Cold Packs - Neck & ShoulderDesigned 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.