20x20x5 (4 3/8) Honeywell/Lennox Replacement Furnace Filters MERV 13 Plus Carbon 4 Pack lighting some growers place the spray

some growers place the spray stake near the edge of the pot

brown scarring

resists water

CES pH Down™

Black & White Panda Film 50'x100' 7mil

20x20x5 (4 3/8) Honeywell/Lennox Replacement Furnace Filters MERV 13 Plus Carbon 4 Pack lighting some growers place the sprayImportant 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. We also carry 4 7 8 and 5 1 4 inch depth filters,