F3 premium RZ« filter, combines the best technologies from the F1 and F2 filters High Flow + Active Carbon Filter First layer is a High-Flow Electrostatic Filter, trapping particulate down to .1 micron in size (with 40% better breathability than the RZ« standard F1 filter) Second layer is an Active Carbon Element, which helps to reduce harmful fumes and odors Best-in-class filtration with 360-degree seal Active Carbon Element reduces odors Surpasses the N95 standard, filtering up to 99.9% of particulates down to .1 micron in size (400 times smaller than a human hair) Common use: High intensity, Dust/pollen/smoke/fumes/odors Choose the filter that matches mask size. FILTER F3 HIGH FLO LG 3PK