dhl ship300 filter 1 pcs replaceable pad for face mask pm2.5 with activated carbon dust pm 2.5 s air mask

300 1 pcs replaceable pad for famask pm2.5 with activated carbon dust pm 2.5 s air mask o.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.