The HEPA Filter Assembly is the last stage of ProTeam's Four Level Filtration system essential to improving Indoor Air Quality. As part of ProTeam's Four Level Filtration system, this HEPA Filter is the last filtration stage designed so that all particulate drawing into the vacuum is expelled through the HEPA Filter. - Fits: QuietPro CN HEPA, Four Level Filtration - ProTeam Four Level Filtration system provides advanced protection against there introduction of pollutants back into an environment. Partners in an educational campaign about Indoor Air Quality issues. The American Lung Association does not endorse products.