Koch Filter Corporation BioMAX HEPA Filters are designed to provide the highest level of filtration available for commercial and industrial applications. They are widely used in hospitals, clean rooms, pharmaceutical plants, and in hundreds of other systems where clean air is critical in the protection of people, processes and equipment. BioMAX HEPA Filters are constructed using the highest quality components available and are available in efficiencies of 99.97%, 99.99% and 99.999% on 0.3 micron size particles. Standard construction BioMAX HEPA Filters are manufactured with galvanized steel cell sides (UL Class 1) or particle board cell sides (UL Class 2). Multiple cell side options are also available. Koch Filter® HEPA Air Filter, Standard Capacity, Series: BioMAX™, 24 in Width, 5-7/8 in Depth, 18 in Height, MERV: 15, 420 cfm, SBW Style, 0.9997 Efficiency, 1 in WG Initial Resistance, Ultrafine Glass Fiber Paper Media, Domestic