The hot& cool packs are made of ores (jade, amethyst, yellow ocher and mineral stones) which emit healthy far infrared rays.The products can be used all year round after being boiled in water, warmed in a microwave oven or kept in a refrigerator. They help prevent adult diseases and relieve pain.- Far infrared light emitted from ores can penetrate any material except aluminum.- When the pack is heated far infrared rays increases 2~3 times.