Usage:This non-toxic and non-caustic gel pack can be used as a hot or cold compress. 1)To warm, place pack in microwavable container, set the microwave at medium power ,and heat pack at 30 second intervals until desired temperature is achieved. Or cover pack completely with 80 - 90癈 water and soak for 3 - 5 minutes. 2)For cold compress, place in freezer for one hour before using. Function: The theoretical basis of cold compress: microcirculation vessels contract during the cold compress by means of the stimulation of coldness and the penetration of energy, influences the organism system, triggers the feedback reaction of nerves and body fluid, strengthens the metabolication, significantly activates the body defensive system and makes the antibody active. The series of functional responses improve the human body health condition as a whole These cold packs are used to reduce inflammation and swelling by lowering skin temperature. Additionally, they are used to help relieve pain by numbing injured tissues and reducing muscle spasms. This product is ideal for sprains, strains, contusions, minor burns, toothaches, simple headaches, insect bites and many first aid needs.