This filter is located under the dust bin. Remove the dust bin then check for where the air is being exhausted. For best cleaning results, change this filter every 3-6 months. When you notice the suction on your vacuum decreased, clean or replace the filter. (Make sure it is totally dry before replacing it in the vacuum.) HEPA filtration systems trap and seal-in 100% of dust mites, pollens, ragweed, mold spurs, microscopic particles, bacteria, dust mites, germs as small as 0.1 micron., other allergy causing agents, and 99.9% of pet dander.