So that dust stays safely enclosed

The Miele AirClean filter system consists of a genuine original Miele dustbag, a motor protection filter and one of the genuine original Miele exhaust filters. These three filtration levels ensure that the vacuumed dust cannot escape. The room air is even cleaner than before and it takes longer for dust to settle again on furniture and surfaces. You can choose between three types of Miele exhaust filters to meet your individual needs:
AirClean filter
Effective filtration for everyday needs.
>99.9% overall dust retention capacity* in combination with the HyClean dustbag and motor filter.
Active AirClean filter
Significant reduction of unpleasant odours* - ideal for pet owners or households with smokers.
Active HEPA filter
Filters even fine dust and allergens - ideal for those with house dust allergies.
> 99.99% overall dust retention capacity * of the vacuum cleaner, as well as HEPA 13 classification *.
Our recommendation for people with allergies
People with house dust allergies should look for a vacuum cleaner with a HEPA filter fitted as standard and specially sealed casing. These appliances guarantee that the air expelled from the vacuum cleaner is actually cleaner than usual indoor room air. Based on these characteristics, some Miele vacuum cleaners are specifically recommended for people with allergies. In order for the appliance to maintain high filtration performance throughout its service life, the saturated, clogged HEPA filters must be replaced regularly - about once per year. 
According to EN 60312-1According to DIN EN 13725Images serve as examples to illustrate the product benefit. Actual feature may vary per model.