This optional exhaust filter combines two Super Air Clean filters with a thick layer of Activated Charcoal to provide heavy duty trapping of unpleasant odors. This is recommended of pet owners who desire better odor control. The completely sealed systems in the ART. by Miele model S930 and S938 vacuums, when equipped with this exhaust filter, will provide outstanding filtration plus excellent odor control.This filter fits in the same place as the Certified HEPA or Super Air Clean Filter. You can not use more than one exhaust filter at the same time.