Medical Filtration Technology - Lab tested Medical Composite filtration technology in 6 layers of filters and high-tech liquid silicone, High Protection against gases, smells, all PM; PM2.5, PM0.3, pollen, smoke and pathogens such as viruses and bacteria Durable and Comfortable Material - Our super leading anti- pollution mask comes with liquid silicone in all round sealing feature to perfectly fit for face shape, and durable adjustable silicone straps, makes it in high top-rated quality,suits for travel and sport, especially to ,some area of USA,China or India The mask uses a unique Six layers filter system(much more than three layers). The First three layers - Skin friendly polyester layer, Anti dust cotton and Spray layer, catches larger pollution particles such as dust and PM10, followed by the Three-Ply Micro Particulate Filter which stops nearly 100% of smaller particulate matter such as PM2.5 and PM0.3. The Fourth and Fifth filtration layers - HV electrostatic cotton and Antibacterial layer are made from a 100% pure activated carbon cloth, The filter, it can be used for 100 - 200 hours on average depending on the level of pollution it is used in. How to tell the filter need to be replaced? Generally, there are 2 aspects to know whether you need to replace the filter core: the first way is to observe with your eyes, when the white filter is obviously get yellow, you need to change it; the second way is about respiratory resistance, if you feel the significant increase in respiratory resistance for the filter, please change it in time.