21x21x1 Electrostatic Washable Permanent A/C Furnace Air Filter - Reusable - GOLD FRAME Traps 95% of airborne dust and allergens Permanent & Washable - Just hose off and reinstall Replaces disposable furnace filters - Lifetime Warranty Made with a premium quality extruded aluminum, gold anodized frame with a durable and attractive finish. Self-charging electrostatic filter media - does not require electricity