Clarke 147125060 CarpetMaster vacum HEPA exhaust filter is a commercial-grade replacement HEPA filter that traps dangerous spores, pollen & particulates that can trigger asthma.  Meet your moral duty to protect those -- including yourself -- who can't protect themselves.  Installs quickly and easily in your CarpetMaster vacum cleaner.  Top Choice:  Hospitals, Nursing Homes, Schools, Day Cares, Resorts & Hotels, Restaurants, Stadiums, Airports, Theaters, Military, etc.  HEPA filters need to be changed every 90-120 days.  When safety & health of others matters more . . . .