Large Three Layer Performance Air Filter:This aFe POWER Pro DRY S is a 7-1/2” tall, oil-free, 360-degree radial flow performance air filter with three layers of synthetic media for maximum convenience. Its progressive layering provides great filtration efficiency and dust holding capacity, while not requiring the use of oils. This media is best suited for street and light off-road use. Its inverted top makes for more filter surface area, resulting in more flow and longer service intervals.