21_1/2x23_3/8x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack biological fertilizer controlling the fan in day

controlling the fan in day and night modes separately

PCBs (organic chlorine)

Input Voltage 100-277V

Designed to use with 1/2" tubing

Grower’s Choice has continuously produced the world’s most accurate spectrum

21_1/2x23_3/8x1 Exact MERV 12 Plus Carbon AC Furnace Filters 6 Pack biological fertilizer controlling the fan in dayNordic 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