These are rice filled microwavable heating pad or put in the freezer for a cold pack.
Heat, put in microwave for 2 mins and make sure its not to hot before use, if it is, let it cool, and you can use on your neck, back, legs, arms, and stomach
Cool, strain muscles and sore areas, after a work out.
The purpose for these packs,
Sore Muscles and Joints