This filter features five layers of pre-oiled cotton gauze media to provide maximum performance. Its progressive layering allows the filter to flow at high levels even when dirty. This media is perfect for street and/or track use. Pro 5R filters are easily recharged with aFe's POWER CLEANER and blue air filter oil. aFe POWER performance air filters use a rounded, evenly spaced pleat design which allows for more usable filter surface area, providing increased flow and greater dust holding capacity. This aFe POWER performance air filter is constructed with a polyurethane base and top. This construction allows for a proper factory style fit with excellent filter strength. Its inverted top makes for more filter surface area, resulting in longer service intervals. Utilizing the filter's retention groove, the filter locks into most Stage-2 housings with zero hardware. This simple design allows for easy filter maintenance and replacement.