F1 Mask Filter consists of two layers: particulate filter and Active Carbon Element Best-in-class filtration with 360-degree seal Active Carbon Element reduces odors and fumes Surpasses the N95 standard, filtering up to 99.9% of particulates down to .1 micron in size (400 times smaller than a human hair) One-way discharge valves reduce moisture Superior protections and won't fog glasses Common uses: low intensity dust/fumes/odors/smoke/pollen Choose the filter to match mask size Sold in packs of 3 or 12. FILTER F1 CARBON XL 12PK