The NanoProtect HEPA filter captures 99.97% of all particles down to 0.3 um, such as common allergens, dust, dirt, bacteria and some viruses. Thanks to the lifespan of 24 months, you can continue to enjoy it for a long time. The Philips FY3433/10 NanoProtect air cleaning filter is a replacement filter suitable for the Philips AC3256/10 air purifier. , The Philips NanoProtect HEPA filter has multiple optimized folds. This concerns an unfolded area of ??approximately 2 square meters to ensure a long life. The Philips NanoProtect HEPA series 2 filter is made of high quality material. It can capture up to 99.97% of particles even as small as 0.3 microns the size of the most common airborne allergens, harmful particles, bacteria and viruses. The high-quality filter with firm and stable structure ensures that all air flows through the filter and provides high filtering efficiency.