[Compatible Model]This product is 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 [ combo set]Keep your home clean This set can cater to your needs for up to one and a half years, offering both cost-effectiveness and convenience for all your replacement requirements [Washable & Reusable]Maximize cost-efficiency by rinsing our filters thoroughly with clean water, allowing them to dry thoroughly, and reusing them. For performance, we recommend replacing the filter set every 2-3 months to help extend the lifespan of your vacuum cleaner [Premium Material] The replacement pre-motor filter assembly is made of high-toughness foam , specifically designed for use with your Cordless Auto-Empty System. Please note: the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:Photo Color Material:sponge Package Contents: 6Pack x Pre-Motor Foam & Felt Filter Kits Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.