Lennox 26Z89 - 20" x 22" x 5" Healthy Climate HCF19-11 Air Filter, MERV 11

Nominal Size: 20x22x5 Actual Size: 21.63 x 19.94 x 4.38 MERV 11 Manufacturer recommended replacement every 6 monthsYou may also like Lennox X0585 (5-Pack) - 20" x 20" x 5" Healthy Climate Replacement Filter, MERV 11.