Making a HealthPro series air purifier that removes low-level gas and odors in addition to allergens meant designing a unique filter that compliments the PreMax pre-filter and HyperHEPA filter. IQAir engineers accomplished that by combining two types of media-one that adsorbs odors and gases and another that changes the pollutant to an oxidized form. They called it the V5-Cell. The "V" refers to the five V-shaped filters that make up the V5-Cell. It"s these V-shaped filters that hold over 5 pounds of carbon mixed with alumina based potassium permanganate in such a manner that air flow is not decreased more than 20 cubic feet per minute when passing simultaneously through them. As a result, the filtration of the HealthPro Plus, which comes standard with the V5-Cell, and the HealthPro, which has space for the V5-Cell as an optional upgrade, removes more than 200 pollutant gases and odors from your home down to 0.003 microns with a guaranteed minimum efficiency of over 99.5%. The outcome is air as clean as it smells.