This RZ F2 High-Flo Electrostatic Filter promotes 40% better breathability than the standard F1 Active Carbon Filter. This High-Flo filter offers a 97% filter efficiency rating against particles as small as 0.1 micron, such as dust, pollen, airborne pollution and most smoke particles. Filter does not contain an active carbon filter layer, so it cannot filter fumes, odors and organic chemicals. Pack of 3 filters. For use with RZ Dust Masks. Masks sold separately.