3 layers pm2.5 original filter safety mask gasket anti dust breathable mouth face mask replacem v4sz

3 layers mouth mask gasket safety anti dust breathable mouth famask replacement pad mat 9.1.the first layer: high efficient filter cloth filter the dust of micron.2.the second layer: meltblown cloth to filter industrial pollutants, automobile exhaust, second-hand smoke pollen allergies.3.the third layer: high efficient filter cloth filter benzene and a smaller function of filtering dust microns.4.the fourth layer: activated carbon cloth filter density, sma.