Lennox X0445 MERV 10 Filter for PMAC-20C - 25" x 20" x 6" - Genuine Lennox Product MERV 10 Nominal Size: 25&quot; x 20&quot; x 6&quot; Captures particles down to 0.3 micron Needs to be replaced every 12 months Pleated Air Filter for PMAC-20C