Hot and cold therapy work cohesively to help you recovery faster. The reusable pack is so easy to use! Pop the pack in the freezer for cold therapy, and pop it in the microwave for heat therapy – simple! Medicare Reusable Hot and Cold Pack provides relief from strains and pains. Heat Therapy: for effective relief from muscular aches and pains, joint stiffness, backache, strains and sprains. Cold Therapy: for fast relief from sprains, strains, bruises and swelling, headaches and minor injuries. Depending upon the ambient temperature, the hot and cold pack can remain hot for up to 40 minutes and can remain cold for up to 2 hours.