For Models:CMF1620A replace with Part #M0-1056CMF1625A replace with Part #M1-1056CMF2020A replace with Part #M2-1056CMF2025A replace with Part #M8-1056 Accessories Activated Carbon Filters (3 per pack) help eliminate unpleasant odors. Replace every 3-6 months. For Models: CMF1620A/ CMF1625A Part #1156-3CMF2020A/ CMF2025A Part #1856-3 Upgrade Kit to Electronic Air Cleaner includes Prefilters (2), Collecting Cells (2), Power Box (1) including Air Proving Switch and Contact Board: EACK1620A upgrades to SAS-10ASEACK1625A upgrades to SAS-11ASEACK2020A upgrades to SAS-12ASEACK2025A upgrades to SAS-18AS * MERV: Minimum Efficiency Reporting Value. Based on ASHRAEStandard 52.2.