Phat Filter, 10" x 39", 1400 CFMPhat Filter is the professional grade greenhouse air filter on the market. It utilizes a special virgin charcoal carbon (RC 412) to eliminate the particles and odors from the air. Carbon dates back 250 million years. This special feature makes the Phat filter so effective. The package comes with a pre filter to eliminate the large sized air particles. It is great to use for grow operations because it provides plants with the clean and fresh air