Far infrared ray (FIR) is an electromagnetic wave that is emitted from the sun, and is also known as growth light, heat light, and life light. It is an invisible heat energy that has the longest wavelength of all infrared rays, and possesses excellent heating characteristics. 
These far infrared rays also aid in many life sustaining functions; improving blood circulation, increasing and maintaining body temperature, keeping harmful germs and molds from growing and spreading, promoting and activating plant growth, cleaning dirty air and promoting body metabolism.