20x20x4 (3 5/8) Pleated MERV 8 Air Filters 6 Pack chillers-heaters-and-purification which provide a gradual ramp-up

which provide a gradual ramp-up and down at both ends of your photoperiod

Converts with a switch from sodium to halide

The GC1 has a 0

rugged handles with reinforced stitching provide portability and greater weight support

With powder coated steel to ensure a long life

20x20x4 (3 5/8) Pleated MERV 8 Air Filters 6 Pack chillers-heaters-and-purification which provide a gradual ramp-upImportant 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