ThermaKool reusable gel packs are designed to provide comfortable pain relief when cold or hot therapy is required. ThermaKool remains flexible when frozen for up to 30 minutes and is safe for microwavable use. Use cold for the treatment of sprains, strains, headaches, contusions, bruises and minor bleeding/burns. Use hot therapy for temporary relief of muscle stiffness, aches and pains. Hospital proven, latex free, non-toxic and easy to clean for reuse. Preferred by School Nurse!