Therapeutic Gel Pack Applies Heat Or Cold To Sore Muscles. Microwave And Freezer Safe. Reusable And Non-Toxic. Instructions Printed On Reverse Side. PLEASE NOTE: After freezing, stays cold for up to 3 hours. If dropped, the item will not shatter or break. After microwaving 30 seconds, the item will stay warm for 90 minutes. Condensation may potentially cause bubbling until cool. CAUTION: Product will be HOT after microwaving.