PM2.5 activated carbon replaceable anti haze filter. First layer of spunbond cloth filters micron-level dust. Second layer filters industrial pollutants, automobile exhaust, second-hand smoke, and pollen allergens, third layer of activated carbon cloth filters micron-level dust, fourth layer offers filter density for smaller material. Fifth layer of spunbond cloth filters out all kinds of harmful substances. Multiple protection to isolate dust, multi-layer folding, good ventilation, double your protection with an additional filter. Filters size: 12x 8 cm/ 4.7 x 3.1 inches.