Pro 5R Filter Media: These filters feature five layers of pre-oiled cotton gauze media to provide maximum performance. Their progressive layering allows the filters 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. Click here for more information about our filter media. Rounded Deep Open Pleats: 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. 100% Polyurethane Base & Top: These aFe POWER performance air filters are 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.