16x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filter 1 Pack microbial fertilizer and some russet mite species

and some russet mite species

For use with reservoirs up to 200 US gal/760 L

and takes 3U of rack space

- 90 - 99% Light Deprivation

Repeat applications every 4 weeks

16x20x4 (3 5/8) Pure Carbon Pleated Odor Reduction Merv 8 Furnace Filter 1 Pack microbial fertilizer and some russet mite speciesImportant 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