DESC: The Active H.E.P.A. (High-Efficiency Particulate Air) filter not only captures and retains tiny, lung-damaging particles (including dust mite feces and pollen), it also uses the same Generally Activated Charcoal filter (GAC) that the Active Air Clean filter uses to absorb odors. This Miele filter conforms to the new stringent European standard for filtration (EN 1822). The Active HEPA Filter is an optional exhaust filter for Miele series S300 through S600 canisters. The sealed system in Miele vacuum cleaners retain 99.97% of pollens, household dust, dust mite droppings and other allergens as small as 0.3 m in size when equipped with a Certified HEPA Filter. This filter is highly recommended for people with dust related allergies or asthma.