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 pliable sealing surface conforms to even the most uneven filter housing, making for a perfect filter fit and sealing surface every time. This design eliminates the use of gaskets or sealants and always goes back to its original form. All aFe POWER flat panel performance air filters are constructed with a full 360-degree polyurethane frame. Unlike other materials that degrade after repeated heat cycles in an engine bay, polyurethane maintains its original molded shape. Magnum FLOW OE Replacement Air Filter w/ Pro 5R Media Subaru Impreza 17-23/Crosstrek 18-24/Forester 19-24/Ascent 19-23/Legacy 20-23/Outback 20-23 Subaru Impreza 17-23/Crosstrek 18-24/Forester 19-24/Ascent 19-23/Legacy 20-23/Outback 20-23