These filters feature three layers of oil-free synthetic media and requires no oil during maintenance to provide maximum convenience. Their progressive layering provides great filtration efficiency and dust holding capacity. 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. 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.