20x20x4 (3 5/8) Pleated MERV 14 Air Filters 1 Pack Promote TDS readings are performed by

TDS readings are performed by an amperometric graphite electrode that resists oxidation

Maintenance is a breeze

Trinity can be used with any nutrient program

Simple Installation

The 020-APHEC-1 features a large LCD display that can be seen from a distance

20x20x4 (3 5/8) Pleated MERV 14 Air Filters 1 Pack Promote TDS readings are performed byImportant 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