Longer lifetimePhilips NanoProtect S3 filter has multiple optimized pleats. This covers an unfolded area to ensure a long lifetime.Superior performancePhilips NanoProtect S3 filter is made of high-quality material. It can capture small particles - the size of common airborne allergens, harmful particles, bacteria and viruses. The high-grade filter with firm and stable structure ensures all the air flows through the filter and delivers high filtration efficiency.