This PM2.5 filter is for use with the "Seesagagi" heat exchange ventilation system without duct. Permanently charged fibers, trap and purify the air in your room by capturing particulates larger than 0.1 micrometer (including pollen, dust mites and droppings, pet hair, dander, asbestos, yellow sand and mold spores. If you are concerned about the effects of life (cleaning the room), or when the pollen is shattering. 1: Does not collect gas ingredients such as cigarette smoke smell or carbon dioxide. It is highly breathable to prevent significant loss of the ventilation volume.