dhl shipboxed 50 pieces non-woven replacement mask inner pm2.5 filter active carbon pad three-layer

boxed 50 pieces mask non-woven three-layer mask replacement mask inner pad three-layer p.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.