AAF Flanders 12 in. x 20 in. x 1 in. Nested Fiberglass Merv 4 Air Filter

This is a standard grade furnace filter of the same type that has been protecting furnaces and central air conditioners around the world for over 50-year. The filtering medium is continuous filament spun glass. The frame is made with 1 continuous piece of chipboard to guard against corner separation. For peak equipment protection and energy efficiency, these filters should be changed monthly in periods of high use. Buy a case and be set for the year.|Lasts up to 30-days|Change filters monthly for peak energy efficiency|Low airflow resistance|UL class II|For furnaces and central air conditioners|UL Listed for safety