20x25x1 Electrostatic Washable Permanent A/C Furnace Air Filter. Traps 95% of airborne dust & allergens. Why buy a new filter every 3 months? This filter is permanent & washable. To clean just hose off the filter, let dry for 15 minutes & reinstall it! This filter replaces disposable furnace filters. These filters have antimicrobial media (inhibits growth of bacteria and mold on filter media). Merv 6 at 500 FPM when the filter is clean. Exact Dimensions: 19-5/8 X 24-5/8 X 7/8. Self-charging electrostatic filter media (does not require electricity). Designed & Engineered by Crucial Air.