21x21x1 MERV 13 Plus Carbon AC Furnace Filters 6 Pack Reflective & Greenhouse Films BotryStop makes an exceptional resistance

BotryStop makes an exceptional resistance management tool as

When used as a soil conditioner

Citric acid 4

Inside diameter 14in

Add the packet to the buffering solution

21x21x1 MERV 13 Plus Carbon AC Furnace Filters 6 Pack Reflective & Greenhouse Films BotryStop makes an exceptional resistanceNordic 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