Aprilaire 2210 Whole House Air Purifier w/MERV 13 Filter Aprilaire Model 2210 is easily adaptable to upflow or horizontal duct configurations Unit operation is completely silent Traps 98% of visible airborne dust and other large particles Permanently captures at least 97% of airborne pollen-sized particles Provides more than 30 times the filtering media used in standard 1" furnace filters Requires no maintenance other than the infrequent replacement of filtering media every 1-2 years Maintains and improves its filter media efficiency over time