filter activate pm2.5 carbon for s original n90 safety mouth face mask replacement pad sq 4c1h

s for n90 safety mouth famask replacement pad square replaceable mat z.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.