Features: 1Compatibility: This air purifier composite filter set includes 3 filters and is specifically designed to fit for Blueair air purifiers including models 503 501B 550E and 603. 2Particle Removal: The air purifier filter is designed to effectively remove large particles and common pollutants in the air including dust particles bacteria pollen smoke odors pet dander and more. 3High Efficiency Microfiber Filter: This fine composite filter can reduce unnecessary odors in living spaces such as volatile organic compounds smoke and common household smells. 4Proper Sealing for Longevity: The filter is securely sealed to protect its lifespan. Regular replacement is recommended to keep your machine clean. For optimal performance it is suggested to disassemble the filter and gently clean it with a soft brush or vacuum once a month. 5Easy Installation: The filter is incredibly easy to install requiring no complex procedures. It provides a comfortable living environment for you and your family and can be replaced within minutes without the need for any special tools. Specification: Item Type: Air Purifier FilterMaterial: High efficiency particulate air filterWeight: Approx. 3200g/112.9ozProduct Size: Approx. 23x33x7cm/9.1x13.0x2.8in Package List: 3 xAir Purifier Filter Note: Note:Please take the new filter out of the plastic bag before putting it in