AEM’s DRYFLOW Synthetic filter eliminates the hassle of re-oiling after cleaning and has better filtration and dust trapping capabilities than any other performance aftermarket filter. Our unique non-woven polyester element filters out 98.6% of airborne dust in initial efficiency (99.4% cumulative efficiency) in independent FINE DUST testing, and filters dirt as small as ONE MICRON of particulate! For comparison, a human hair is about 100 microns thick. This improved efficiency translates into longer engine life by keeping more ring- and seal-eating dirt out of your engine, with no degradation in engine power compared to oiled air filters.