1-Pack The HF-1 HEPA Filter Cartridge For Eureka upright models 6140 - 6160 and 6235 series. As well as, Home Cleaning System Models 6100, 6230, 6235, 6500, 6510, 6978, 6984, 6983, 6980, 6990, 6994, 6997, EL8500AZ, 6991, 6992, and 6993 series. For optimum performance, change your filter every 6 months