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. Black Pro 5R filters are easily recharged with aFe's POWER CLEANER and black air filter oil. Click here for more information about our filter media. 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.