BLUEAIR Blue Pure 411 Auto, 411, 411+ Genuine Replacement Filter, Particle and Activated Carbon, fits Blue Pure 411 Auto, 411 and 411+ Air PurifiersCOMPATIBLE WITH ENTIRE BLUE PURE 411 AIR PURIFIER LINE: Blueair Combination Particle plus Carbon Replacement Filter compatible with entire Blue Pure 411 air purifier line consisting of Blue Pure 411 Auto, Blue Pure 411, Blue Pure 411 plus air purifiers FILTERS BUILT TO LAST: Using a 360 degree air intake and up to 4x the filter surface area the Genuine Blue Pure 411 Particle and Activated Carbon Filter lasts on average 6 months to a year; optimizing