The completely sealed system in the Miele S140 to S150 Little Giant and Universal Uprights, when equipped with a Certified HEPA Filter, will retain 99.97% of pollens, household dust, dust mite droppings and other allergens as small as 0.3 µm in size. This filter is highly recommended for those who have dust related allergies or asthma. This filter replaces Miele #04714431 & 04714432 filter.