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, while its inverted top makes for more filter surface area, resulting in longer service intervals. This media is best suited for street and light off-road 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 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.