18x28x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack Trimmers - Economical

- Economical

Two separate set points can be adjusted from 4 to 7 pH and 900 to 1800 ppm (mg/L)

No phytotoxicity detected in numerous evaluated crops

On-Board Digital screen reporting

• Dimensions: 18

18x28x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack Trimmers - EconomicalNordic Pure Custom MERV 12 Plus Carbon air filters are made based on the actual measurements so be sure to measure your current filter to get the EXACT dimensions before ordering. As with all Nordic Pure filters, the effective life of your filter depends on the environment in which you live. We recommend changing 1 and 2 filters every 30 90 days. Our 4, 5 and 6 inch thick filters could last up to 6 months. EXACT MEASUREMENT: Furnace and air condition