20x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filter 1 Pack Grow Strong They can be easily mixed

They can be easily mixed with other media for increased aeration and added moisture-holding capabilities

Manual control is particularly useful during maintenance operations

your cuttings will benefit from a sterile blade surface that reduces the risk of infection and shock

or 20 trays

Adjustable air outlet

20x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filter 1 Pack Grow Strong They can be easily mixedImportant 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