The RAM Pro Active Carbon Filter Range is a professional range of filters designed with the grower in mind. Guaranteed to do the job, it is easy use, offering value for money and flexibility. This range is offered in a variety of sizes. This filter uses virgin Australian RC412 Carbon, widely considered to be one of the superior carbons for air filtration. It has very low ash content (less than 13%) and it is a virgin-granulated product so that it can be compacted very tightly, meaning that it leaves no air spaces for organic compounds (odours) to escape. The RAM Pro Active Carbon Filters feature a very high specification carbon pore size of 0.02 micron, making it far more absorbent of volatile organic smells and more attractive to them, so that the odour elements stick like glue and become absorbed. Inline drying and dehumidifying is used in the filling process to make sure the carbon is in peak condition before the filter is compacted and special expansion foam on the neck makes sure that the compaction rate of the carbon remains high at all times. You should avoid the various lower quality filters that are currently on the market as they have poor compaction, which will allow volatile smells to escape before they make contact with the carbon.