Smartvent filter ventilation filter $60compatible with smart vent with unique moisture resistant media 150mm x 300mm x 300mm high quality filter media designed to capture dust, pollen & allergens with an 80 90% arrest of particles of 0. 4 microns and above. The Supercell filter cartridge has media that is designed to handle humidity & damp winter air better than anything thing else in this range. This is a perfect fit for smart vent systems and is an upgrade on bag filters if you want