F2 is our High Flo Filter, made up of 2 layers of particulate filters. The F2 is capable of trapping particulates down to .1 micron in size. *This filter does not contain an active carbon element, eliminating the filtration of fumes and odors. This filter has been laboratory tested to be 97% effective. The High Flo particulate filter promotes 40% better breathability than our standard F1 filter. Common uses: High Intensity, No fumes/odors present.