17-1/4 x 29-1/4 x 1 Electrostatic Washable Permanent A/C Furnace Air Filter 17-1/4x29-1/4x1 Traps 95% of airborne dust and allergens Permanent & Washable - Just hose off and reinstall Replaces disposable furnace filters Lifetime warranty Self-charging electrostatic filter media - does not require electricity