1.Product: 50pcs PM2.5 Activated Carbon Filter Replaceable Anti Haze Filter Paper for Mask,(with 3 Free Blue Masks).  Filters size: 12.9 x 7 cm/ 5.1 x 2.8 inches.
2.First layer of spunbond cloth filters micron-level dust; Second layer filters industrial pollutants, automobile exhaust, second-hand smoke, and pollen allergens.
3.Third layer of activated carbon cloth filters micron-level dust; Fourth layer offers filter density for smaller material.
4.Fifth layer of spunbond cloth filters out all kinds of harmful substances.
5.Note: 1. Filter insert can not be cleaned and should be replaced every 1-2 weeks. 2. When film or sticky sediment stains emerge, please replace the filter.