23_3/4x23_3/4x1Exact MERV 13 Plus Carbon AC Furnace Filters 6 Pack fans-ventilation-ducting Made in Germany and engineered

Made in Germany and engineered in a ISO 9001 certified facility

This stops mold growth while preventing overdrying

enhancing both plant growth and flowering

The result of months of scientific research and trials is Grodan Gro-Blocks Improved with our Advanced Wetting Agent

23_3/4x23_3/4x1Exact MERV 13 Plus Carbon AC Furnace Filters 6 Pack fans-ventilation-ducting Made in Germany and engineeredNordic 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