16x20x4 (3 5/8) Pleated Air Filters MERV 14 Plus Carbon 2 Pack Growing Accessories It is a unique combination

It is a unique combination of pure seaweed extract with readily sequestered iron in an easy-to-use liquid form

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optional calibration and a remote 15' low drift CO2 sensor with photocell

For a limited time

16x20x4 (3 5/8) Pleated Air Filters MERV 14 Plus Carbon 2 Pack Growing Accessories It is a unique combinationImportant 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. If you are replacing a 4 3 8 depth 16x20x4 filter