The Horti-Control Dust Shroom is a reusable foam HEPA filter designed to keep unwanted pests and pollutants out of indoor gardens and air-cooled reflectors. Horti-Control teamed up with the leader in foam filter design to create a filter for indoor gardeners. This revolutionary filter will keep your air-cooled reflectors, inline fans, ice boxes and ducting dust free. It will also keep mold, mildew, pests and bacteria out of your garden!