Compatible 400 Series Replacement filter Compatible with Blueair 400 Series Air Purifier Filter,3-in-1 Pre-Filter H13 True Filter and Activated Carbon Filter. Materials: The Blueair 400 Series replacement filter is made of high-quality H13 material to effectively filter and improve air problems. Multiple scenarios: Compatible with Blueair Classic 400 series filters, suitable for home living rooms, kitchens, bedrooms, offices and interior Spaces with high air quality requirements. Easy to remove and replace: Compatible with the Blueair 400 replacement filter and very friendly to women and seniors, you can easily replace your old 400 series without professional assistance, ensuring worry-free daily maintenance. After-Sales Service: We Provide High Quality, Durable and Long-Lasting Materials To Make Your Filters Last Longer, In Order To Improve the Air Effect with a Fresh Environment, Please Replace 403 filter replacement Around 5-8 Months, Depending on the Usage Environment.