For optimum filtration 3M recommends changing filtrete filters every 3 months. Patented filter technology allows for more air to be filtered. CADR rating, (dust)110, (smoke)110, (pollen)128, combined CADR 348. Suitable for room size 16m2. Filtrete electrostatic filter. Size (H)33.2, (W)21.4, (D)2cm.