The hot/cold gel pack can do both and is durably made and easily washable- so you can use it over and over. If hot or cold therapy becomes uncomfortable remove compress for a few moments then re-therapy. Also ideal as a hot or cold compress for sore muscles or injuries. The hot & cold gel pack is a reusable microwave compress designed to fit the shape of the body wherever you need pain relief. Hot packs can also reduce joint stiffness pain and muscle spasms. hot and cold pack are specially designed for comfortable and convenient application of heat or cold to painful areas of the body. Effective in restoring movement to injured tissue.