Lennox Healthy Climate 15" x 20" x 1" replacement furnace filters. Merv 8 filtration in a 1-inch thick replacement filter. This filter is an excellent choice to upgrade from the generic fiberglass filters in your local hardware store. This product is straight from the manufacturer, Lennox, one of the most respected names in home comfort and indoor air quality. Click Here for the Lennox MERV 8 Air Filter Product Brochure