This filter features three layers of oil-free synthetic media and requires no oil during maintenance to provide maximum convenience. Its progressive layering provides great filtration efficiency and dust holding capacity. This media is best suited for street use. Pro DRY S filters are easily recharged with aFe's POWER CLEANER. 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. Just like our air filters, this 1/2” open cell polyurethane foam Pre-Filter is washable and reusable. Easily remove the ABS plastic retainer (patent pending) and foam Pre-Filter then just simply tap to remove excess debris between your usual cleanings. The foam Pre-Filter can also be washed with aFe POWER Cleaner when you service your air filter. Pre-Filters provide added piece of mind for those who operate their vehicle in dirty environments. This foam pre-filter captures large particles before they reach the air filter – increasing efficiency and dust holding capacity, without negatively affecting airflow.