Serenity hot and cold reusable gel pack. This handy sized gel filled pack can be used as a hot or cold compressor for small areas or as a hand warmer in the winter. For hot pack, simply place in microwave container with water for 30 seconds until reaching the required temperature. For use as a cold pack, place in the freezer for 2 hours. Easy to use and reusable. Instructions included. PVC Plastic.