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 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. Unlike other materials that degrade after repeated heat cycles in an engine bay, polyurethane maintains its original molded shape.