WINTERSTEIGER Face Covering Filter Inserts 10 pk 

These PM2.5 filters are a great addition to our face mask covers. They simply slide right in either side. These filter inserts feature 5 layers of protection with a carbon activated inner layer sandwiched between 2 layers of cotton fabric and a melt blown layer to block most particulates larger than 2.5 microns. These filter inserts are intended to be used for up to 48-72 hours (depending on the level of pollution) before changing out. Filter Inserts are not returnable.