Integrated 3-in-1 filter for Philips air purifiers: AC1711 and AC1715. A three-layer filtration system with NanoProtect HEPA, activated carbon, and pre-filter ensures protection against viruses, bacteria, pollen, dust, PM 2.5, pet dander, and gases. For optimal filter performance, the pre-filter should be vacuumed regularly. Removes up to 99.9% of viruses and aerosols from the air. Lifespan of 12 months. Three filters in one for convenience and outstanding performance. The cylindrical 3-in-1 filter contains all three filter layers, allowing your device to maintain consistently high performance just like on the first day. The optimal combination of activated carbon, HEPA, and pre-filter removes pollutants, viruses, allergens, and bacteria from the air. Replace all three filters at the same time for cleaner air to breathe. The NanoProtect Pro HEPA filter cleans faster than the H13. The three-layer filtration with NanoProtect HEPA, activated carbon, and pre-filter protects you from bacteria, pollen, dust, fine particulate matter smaller than 2.5 μm, pet dander, and gases. The NanoProtect HEPA technology not only captures pollutants but also attracts them through a special electrostatic charge. This results in even faster air purification than with a medically used HEPA H13 filter. Removes up to 99.9% of viruses and aerosols from the air. Captures aerosols, including those that may contain respiratory viruses. An independent test showed that up to 99.9% of viruses and aerosols are removed from the air. Also tested against the coronavirus.