Blueair Pro Replacement Smokestop Filter for Pollen, Dust, Virus, Odors and VOC Removal, Genuine Blueair Filter; Compatible with Pro M, Pro L and Pro XL It is important to only use genuine Blueair replacement filters to maintain optimal performance and warranty. Filters that are not Blueair genuine will void your units warranty GENUINE Blueair Replacement Filter is compatible with Blueair Pro M, Pro L and Pro XL Air Purifier Ensure the correct number of filters for your Pro Air Purifier; The Pro M requires: 1 filters. Pro L requires: 2 filters. Pro XL requires: 3 filters PARTICLE and ACTIVATED CARBON combine to create the Blueair SmokeStop filter that, with the Blueair Pro air purifier, reduces pollen, dust, pet dander, mold spores, bacteria, odor, VOCs, Tobacco smoke and other gaseous pollutants RECOMMENDED to change filter once every 6 months, or dependent on usage. This filter is can be recycled after it's changed