True Blue 220201 Air Filter, 20 in L, 20 in W, 7 MERV, 600 um MPR, Cardboard Frame

90 days filter, 23X more effective than fiberglass filters. Filters airborne allergens including dust, dirt and pollen. Helps reduce dust and dirt build-up in furnace systems and air ducts. Cardboard frame material, made in the USA.