The Phat Filter is a professional grade, world renowned greenhouse filter that will remove the nastiest odors from your growing area to give you peace of mind. Phat filters use a very special charcoal carbon that comes from a source of pre-Cambrian ore, some of the oldest carbon found on earth. Genuine Phat Filters offer quality you can trust through non-pelletized carbon, using no glues or binders thereby increasing the effective filtering capability. We are the most trusted name is greenhouse odor control worldwide! Phat Filters are highly effective, low density virgin carbon (carbon tightly-packed for increased porosity). This allows for greater & more even air movement provided by internal, conical filter base which is manufactured so that no air blows by the filter without being filtered. The outer aluminum mesh provides 53% open area allowing increased air flow. Genuine Phat Filters are immediately sealed after manufacture to help retain moisture, optimize presentation and improve life expectancy.