20x20x4 (3 5/8) Furnace Air Filters MERV 12 Pleated Plus Carbon 2 Pack ventilation Detection - CIS / UV

Detection - CIS / UV / IR / MG / MT

1 x Smoke Detector (MBS-SD)

A quiet dual fan kit to enable you to control the ventilation and air circulation for a wide range of DIY projects

NOTE: This item cannot work with a digital ballast

20x20x4 (3 5/8) Furnace Air Filters MERV 12 Pleated Plus Carbon 2 Pack ventilation Detection - CIS / UVImportant 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