20x25x5 (4 3/8) Lennox X6673_X6675 Replacement MERV 13 Air Filters 4 Pack bloom FDA approved

FDA approved

Minimum operating pressure is 10 psi

Stimulates root growth and builds up hardy

This leads to lack of feeding

Water Soluble Hardener is designed for cool temperature climates

20x25x5 (4 3/8) Lennox X6673_X6675 Replacement MERV 13 Air Filters 4 Pack bloom FDA approvedImportant Note: Almost ALL furnace filters have a different "actual size" than the nominal size printed on the air conditioner filter. It's best if you measure your air filter for the EXACT size and compare it to our "Actual Size" and then you can be sure your A C air filter fits! With the 4" and 5" air filters there is a wider variance between the nominal and actual size depending on the manufacturer. We also carry 4 7 8 and 5 1 4 inch depth filters,