The original Philips filter: Genuine Philips filter was designed together with the device itself to ensure a perfect fit which guarantees the continuously smooth operation of the device Superior performance: NanoProtect HEPA filter's low-resistance fibers maximize the airflow. The electrostatic charge attracts particles as small as 0.003 microns with 99.98% of efficiency Long lasting performance: Philips NanoProtect HEPA filter provides consistent protection and guarantees optimal filtration to up to 2 years Effortless maintenance: Your Philips device notifies you when to clean your pre-filter and when to replace the filter. This takes less than a minute Quality you can trust: Philips air filters go through a set of mandatory and strict inspection tests before releasing from factory. They are subjected to rigorous life and durability tests, for continuous operation 24/7