... for a high concentration of anion with 7 million/cm3. It also installed with corona ozone generatior device with refractory ceramic ... and double ESP electrostalic precipitation, all of which will make it the ideal product for eliminating peculiar odor,purifying air and ... , bed room, bar, hotal and restaurant.No chemical use, no need to open it for repairAir purification and negativeion good for healthe