20x21_1/2x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack spl_hf All mounting screw heads are

All mounting screw heads are black to match the mounting frame

both the individual culture/species as well as the final blend

pumps and fill fittings and the whole thing can automated

You will need either a pump or a valve

20x21_1/2x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack spl_hf All mounting screw heads areNordic 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