21x21x1 MERV 12 Plus Carbon AC Furnace Filters 6 Pack timers-and-instruments 8'' x 8'' and 12''

8'' x 8'' and 12'' x 12'' ensuring we have the sizes you need

Silica also allows for better root development and faster growth

integrated production and world-class R&D

flower and herb gardens as well as in greenhouses and hydroponics

processed and manufactured under strict quality standards

21x21x1 MERV 12 Plus Carbon AC Furnace Filters 6 Pack timers-and-instruments 8'' x 8'' and 12''Nordic 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