Compatibility: The pre-motor filter is compatible with Dyson Big Ball CY22 CY23 CY24 CY25 CY26 CY27 CY28 DY75 DY77 DY78 vacuum cleaners. Washable and reusable: Wash with warm water and let it air dry completely before reusing. A mild detergent can be used if desired. To keep your vacuum working properly and optimally, it is recommended to replace the filter every 4 to 6 months. Premium vacuum filters adopt a two-in-one design with high efficiency to block fine particles, floating dust, etc. The filter is made of high-efficiency filter material, which can effectively filter dust to prevent large dust particles from entering the motor and ensure a long service life of the vacuum cleaner. Package includes: 2 pre-motor filters.