5 layers protective replacement fliter breathable insert pm2.5 filter active carbon mask inner fte6

5 layers protective mask replacement fliter breathable insert mask inner pads pm2.5.1.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.