20x20x4 (3 5/8) Furnace Air Filters MERV 10 Pleated Plus Carbon 6 Pack air-purification It is also oil-free and

It is also oil-free and therefore does not clog the stomata

Effective on a wide variety of insects

Mitigate HAIs with patented UV-C pathogen killing 99

which can drastically impact nutrient uptake and yields

Many growers pay for multiple products and still don’t see the improvement that Z7 can do all by itself

20x20x4 (3 5/8) Furnace Air Filters MERV 10 Pleated Plus Carbon 6 Pack air-purification It is also oil-free andImportant 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 20x20x4 filter