The Dual Filter™ material guarantees the best cleaning results using a combination of HEPA filter and Carbon Weave technology. Carbon Weave increases the amount of activated carbon exposed to the air for superior removal of odors and harmful gases while the HEPA filter removes all other airborne particulate. Features The Dual Filter™ is a combination of HEPA and activated carbon filter The filter material is made in Germany The HEPA part filters pollutants out of the air, such as fine dust, pollen, viruses and bacteria The activated carbon filter adsorbs gases (bad smells, tobacco smoke, formaldehyde, toluene, volatile organic compounds, etc.) The Dual Filter™ has to be replaced every 8–12 months