Laboratory tested by Humboldt Analytics, Phresh Intake Filters will remove 99.7% of air pollution including mould spores, organic and/or chemical compounds of any description. Phresh Intake Filters will filter down to 2 microns and keep your inlet air as pure as humanly possible for a minimum of six months. Stop mould before it even enters your room with Phresh Intake Filters. Our proprietary Activated Carbon Felt will only slow up your fan by a maximum of 18% making Phresh Intake Filters the best choice for intake filtration for indoor greenhouses and tissue culture labs.