[Compatible Model] BU3523 BU3521 BU3120 HEPA filter replacement compatible with Shark BU3523 Clean Lightweight Cordless Stick Cleaner and Shark BU3521 Clean and Empty Cordless Stick Vacuum Auto Empty System. [Value Pack] Includes 2 Pack Handheld Vacuum Pre-Motor Filters, 2 Pack Auto-Empty System HEPA Filters and 2 Pack Auto-Empty System Pre-Motor Filter Assemblies ( 2 Pack Foam filters and 2 Pack Felt filters). [Washable and Reusable] The filter can be cleaned manually, not machine washable. The filter is reusable multiple times and protects your vacuum for up to 60 days. We recommend replacing the BU3523 filter replacement set every 3 months. [Premium Material] The filter is made of high-toughness HEPA filter paper and durable ABS material, which can effectively block up to 99.97% of fine dust, including tiny particles as small as 0.3 microns, pollen and allergens. [Easy Installation] Replacing cordless vacuum cleaner BU3523 parts do not require tools. Simply remove and replace the filters from your vacuum cleaner equipment when needed. Quick and convenient, making your cleaning tasks smoother. 7 Packs Replacement Parts for Shark IW3511, IW111, BU3521, BU3523 Detect Pro Lightweight Cordless Vacuum Cleaner, Compatible With Shark Clean & Empty BU3521 Lightweight Cordless Vacuum Cleaner