A High Efficiency Particulate Air filter, often abbreviated to HEPA filter, is not only part of professional cleaning devices used in hospitals and doctors' practices. Many vacuum cleaners for home use also have such a component that absorbs and stores allergy-inducing dust particles. After a while, however, the filter loses its purifying function and it is time to replace it. For example, with the Scanpart HEPA filter F296 for Miele.
Note: not every replacement HEPA filter will fit every vacuum cleaner. Please read the manual of the relevant device carefully. Here you will find the type number filter meant for your device.