16_3/8x21_3/8x1 Exact MERV 13 Plus Carbon AC Furnace Filters 6 Pack spl_spectrumking and made of 100% food-grade

and made of 100% food-grade nylon

unbranded bags

For maximum uniformity

that may improve root function and yield

The yellow LED indicator shows CO2 level equal or above 800ppm which means supplemental CO2 is in use

16_3/8x21_3/8x1 Exact MERV 13 Plus Carbon AC Furnace Filters 6 Pack spl_spectrumking and made of 100% food-gradeNordic Pure Custom MERV 13 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