The Blueair 650E is �Best in Test� as determined by ETL�s testing for Clean Air Delivery Rate (CADR). It has been certified by the Association of Home Appliance Manufacturers (AHAM) with the highest CADR rating possible in test. The Blueair 650E is ideal for a large living area such as family room, master bedroom suite, any large living area. The e-series continuously monitors and purifies your air using integrated electronic sensors and automatic fan control. Simply set the unit on auto mode and let it regulate the speed according to the actual amount of particles and gaseous contaminants present in the air. The faces on the digital display indicate the status of your indoor quality ---- from sad to happy!