View on LOZ Suggested Retail: $25.88. Nordic Pure 20x20x5 MERV 12 Honeywell/Lennox Replacement AC Furnace Air Filter 1 Pack. Nominal Size: 20 x 20 x 5 H, Actual Size: 19 5/8 x 19 7/8 x 4 3/8 (19.63 x 19.88 x 4.38). Measure your air filter for the exact size and compare it to our actual size to ensure proper fit. Replaces Honeywell 20x20x4 and filters with an MPR rating with an actual depth of 4 3/8 and ideal for high efficiency air filtration and those with moderate allergies.. 7 CALENDAR DAY FULL REFUND GUARANTEE ON THIS ITEM IF ANY ISSUE IS FOUND THAT WAS NOT DESCRIBED/PICTURED. 7 CALENDAR DAY STORAGE IS ALSO AVAILABLE. SEE NOTES TO BIDDER, IN AUCTION DETAILS, AT THE TOP OF PAGE 1 FOR MORE INFO.