10003.9 is a particulate filter for HVAC systems, used for filtration of dust, dirt, pollen, and other airborne contaminants. It works by trapping these particles within a electrostatically charged media, which is then trapped on the surface of the filter. This filter offers the highest efficiency level for dust and other particulate matter. It is also resistant to humidity, bacteria, and corrosion, and is effective for large and small rooms. It is suitable for use with Forced Air and Air Filtration Systems.