Relief from strains, sprains, tendonitis and other injuries. Unique strapping system securely fastens anywhere on these hot and cold packs. Non-toxic gel is biodegradable and retains therapeutic temperatures longer. Soft, plush "frost-free" cover protects your skin. Store in the freezer; stays soft and pliable. Heat in microwave. Heating InstructionsBased on initial pack temperature below 75F (24C). Knead after each heating. Microwave ovens vary; use care when heating and removing pack from microwave. Overheating pack may cause pack to rupture and/or leak. Carefully check the pack with the palm of your hand before applying. Discard pack if punctured or broken. Heat 15 seconds on high heat, knead, and then continue heating at 5 second intervals until desired temperature is reached. Knead after each heating