... good to human health. Descripton for Carbon crystal far infrared Theraphy board Heating elementCarbon crystalHeat transfer98%Size18mm*500mm*380mm ... temperature70 °C - 90 °CThermostat control5 °C - 50 °CFar infrared radiation>95%Service life >100,000 hours or 50 years ... , reliable and long service life. D,Green material, environmental protection. no harmful emissions, no noise, no harmful radiation. E ...