The ULTIMATE Furnace A/C Filter! Washable, Permanent, Reusable. Electrostatic - Traps dust like a magnet. 10x Better than Disposable Filters. Never Buy Another Filter! (20x20x1) Traps 95% of airborne dust and allergens Permanent & Washable - Just hose off and reinstall Drop-in replacment for disposable furnace or A/C filters Made in USA by AIR CARE - Lifetime warranty Self-charging electrostatic filter media - does not require electricity