[Compatible Model] This product is fully compatible with for Clean Cordless Cleaner models including BU3523, BU3521, BU3120. Please confirm that your machine model matches one of our compatible products before purchasing. [Washable & Reusable] Maximize cost-efficiency by rinsing our filters thoroughly with clean water, allowing them to dry thoroughly, and reusing them. For , we recommend replacing the filter set every 2-3 months to help extend the lifespan of your vacuum cleaner. [Easy Replacement & Installation] No tools required for filter replacement. Simply remove and replace the filters from your vacuum cleaner equipment when needed. Quick and convenient, making your cleaning tasks smoother. Please note:the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:As Shown Material:Plastic Package Contents: 2 * hand-held vacuum motor pre-filters 4 sets * automatic emptying system motor prefilter assemblies (4 foam filters and