Compatible Models: The 511 Replacement Filter Is Only Compatible With Blueair Blue Pure 511 Air Cleaner To Maintain Its Peak Performance. Fit Snugly With The Machine. It Works As Well As The Original With The Same Performance, Keeping Your 511 Air Cleaner At Its Best Working Efficiency And Capacity. Any Use Of The Brand Name Or Model Designation For This Product Is Made Solely To Demonstrate Compatibility. | | Not Compatible Models: 511+, 511I Max, And 511 Auto. | | Premium Material: Our 511 Replacement Filter Is Made Of High-Quality Non-Woven Fabric With Premium True Hepa And Activated Carbon Materials To Greatly Improve The Performance Of 511 Filter Replacement. We Adopt Advanced Lower Energy Consumption And Lower Density Structure Technology, Higher Efficiency, And Less Pressure To Ensure High-Efficiency Filtration. | | 3-In-1 Stage Filtration System: Our 511 True Hepa Replacement Filter Is Combined With A High-Efficiency Filtration System That Has 3 Layers Of Advanced Fil.