21x23_1/4x1 Exact MERV 14 Plus Carbon AC Furnace Filters 6 Pack Electrical Components Temperature control range: 40 to

Temperature control range: 40 to 108°F (5 to 24°C)

These paper-wrapped Mini Blocks are designed for seedlings and cuttings

This OMRI listed product can be used as a foliar spray or as a soil drench

Available Phosphate (P₂O₅): 0%

21x23_1/4x1 Exact MERV 14 Plus Carbon AC Furnace Filters 6 Pack Electrical Components Temperature control range: 40 toNordic Pure Custom MERV 14 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