This complete particle filter change kit fits all Blueair 400 Series HEPASilent Air Purifiers (402, 403, 450E), and comes complete with:
1 standard HEPASilent filter of polypropylene (traps particles).
Replace every 6 months.
When the filter needs to be replaced (twice yearly), just open the side, slide out the old filter and drop the new one in. No screws, hooks or tools and less than one minute of your time are required.