16x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filters 2 Pack soil nutruient Enzymes (protease & cellulase)

Enzymes (protease & cellulase)

fit the Circulator into the center holes

High accuracy

and Spring Steel you will get many years of use from this unit

nurseries and indoor growing

16x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filters 2 Pack soil nutruient Enzymes (protease & cellulase)Important 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