Healthy indoor climate thanks to high-quality Philips technology. The improved filters can be used for about 6 months and should then be replaced. Replacing filters on a regular basis ensures consistent performance and quality of humidifier. The 30 mm thick filters are made of PET material with a honeycomb structure of 12 layers. The unfolded area results in 15,662 cm2 - enough space for sufficient water absorption and efficient evaporation.