FLEXIBLE Electrostatic Washable Permanent Furnace A/C Filter - Lifetime Warranty - Permanent Filter that flexes and bends (20x30) It Bends and Flexes and goes where a rigid filter wil not fit Traps 95% of airborne dust and allergens Permanent & Washable - Just hose off and reinstall - Lifetime Warranty Replaces disposable furnace or A/C filters Self-charging electrostatic filter media - does not require electricity