COMPATIBILITY: Our Classic 500/600 Filter Replacement is Compatible with All Blueair Classic 500 600 Series Air Cleaner Purifiers 501 503 505 510 550E 555EB 601 603 605 650E, 6 Pack. Suggestion: The filter can last at least 6-8 months if this air Cleaner purifier runs at the highest speed. Meanwhile, the filter's usage time will depend on the environment and air quality around you. Note: It should be stored in a dry location protected against moisture. Package Contents: 3 x 500/600 Filter element This is not Blueair OEM products. Blueair brand names and logos are the registered trademarks of their respective owners. Any use of the Blueair brand name or model designation for this product is made solely for the purposes of demonstrating compatibility.