Spunbond cloth filters micron-level dust;PM2.5 (Particle matter 2.5 microns);Conforms to standards GB2626-2006;Active carbon cloth filters atmospheric particulate matter;Reduces inhalation of particles such as haze. dust. pollen. and motor vehicle exhaust emissions;Recommended to replace filter every 1 to 3 days. depending on use;1 order unit contains 10filters;Non-returnable;DISCLAIMER: The Premier PM2.5 filter makes no assurances that it can prevent transmission or infection of disease or viruses. The filter is designed to reduce inhalation of particles such as haze. dust. pollen and motor vehicle exhaust emissions. Remove and do not use filter if you are suffering with breathing difficulties or skin irritation.;Information sheet;