16x25x5 (4 3/8) Honeywell/Lennox Replacement MERV 15 Air Filters 4 Pack Environmental Controllers Magnesium is also critical for

Magnesium is also critical for the uptake and migration of phosphorous in plants

no guesswork

Measures 10

1 × Thermometer and Hygrometer

HALO enables the gardener to automate their pH and temperature logging efforts

16x25x5 (4 3/8) Honeywell/Lennox Replacement MERV 15 Air Filters 4 Pack Environmental Controllers Magnesium is also critical forImportant 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,