?Perfectly Compatible With 511I Max?This 511I Max Replacement Filter Is Only Compatible With Blueair Blue Pure 511I Max Air Purifi-Er. Not Fit For Other Models. Please Check Your Model Before Buying. | | ?3-In-1 Filter?Combining The Nylon Preliminary Filter, H13 True Hepa Filter And Activated Carbon Filter. 3 Layer Filtration Attaches 99.97% Of Air Pollutants, Bringing Your Family Fresh And Pure Air. | | ?H13 True Hepa Filter? The 511I Max Air Replacement Filter Has The 99.97% Filtration Efficiency And Intercepts Particles Larger Than 0.3 Microns. Attaches Most Air Pollutants, Such As Dust, Dander, Pollen, Smoke, And Other Small Particles. | | ?Activated Carbon Filter? Premium Granular Activated Carbon Physi