16x20x4 (3 5/8) Pleated MERV 7 Air Filters 6 Pack controllers and the rubber feet minimize

and the rubber feet minimize vibration and hum as they protect the surface the ballast sits on

The Max-Fan® Pro Series is even more efficient and stronger than the original Max-Fan® design

this may help you obtain glorious gardening results and save water at the same time

Hands-free monitoring and dosing of solution pH levels

Available Phosphate (P2O5) 1

16x20x4 (3 5/8) Pleated MERV 7 Air Filters 6 Pack controllers and the rubber feet minimizeImportant 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