Dynarex Instant Hot and Cold Packs are designed to help offer quick relief to minor injuries, stiff joints, muscle aches, and cramps with a single hot or cold pack. The Packs are crafted from flexible materials to closely conform to body contours for effective treatment and added comfort. The Packs are activated by a simple squeeze for use in 30 seconds. The Dynarex Instant Hot and Cold Packs are conveniently sized for easy portable for first aid kits, sporting events, schools, and home use.