Warm them in the oven or microwave (don"t over heat them) they should be hot to the touch but not hot to burn you. They should be like a hot springs or spa...Salt therapy naturally helps detoxify your body, support normal blood circulation, promote enhanced well-being and improves sleep quality!Salt therapy has been around since the mid 1800s and in Europe salt spas are common. Now you can bring the natural health-enhancing benefits of salt therapy to your home. These salt crystal foot blocks are crafted from specially-selected salt crystals from the foothills of the Himalayan mountains, home of the world"s purest salt. Just warm them in your microwave, rest your feet & let the healthful benefits begin.