Remains warm for up to 20 minutes. Use on sprains, strains, dislocations, swelling, bumps and bruising, minor burns, insect bites and stings, headaches, migraine and tension relief, muscle aches and spasms, cramps, toothaches and sinus congestion. Hot Packs are ideal for sporting activities, industry, health clubs, schools, automobiles, first aid kits, home and cottages.