16x20x4 (3 5/8) Pleated MERV 7 Air Filters 1 Pack hydro-systems The fossilized kelp is full

The fossilized kelp is full of vitamins

14% drier than competitor blocks

commonly known as “red wigglers” and technically known as Eisenia fetida

Works on most common weeds like Nutsedge

The quality construction features a highly reflective specular aluminum interior reflector

16x20x4 (3 5/8) Pleated MERV 7 Air Filters 1 Pack hydro-systems The fossilized kelp is fullImportant 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