By using PowerCore Air Filters, submicron contaminants load on the surface rather than collecting in the depth of the filter. This boosts efficiency and increases performance on your aftermarket air intake system. The filter media won't deteriorate as easily as traditional cotton/gauze filters. Plus, it's water resistant, so getting wet won't ruin your air flow or cause a decrease in performance. This is why we warranty our replacement air-filters for 4 years or 100,000 miles in urban conditions, whichever comes first.