Large Five Layer Performance Air Filter:This 7” tall 360-degree radial flow air filter features a 3-1/2" flange and our pre-oiled Pro 5R media with five layers of progressively finer cotton gauze media for maximum performance. It provides your engine with the largest amount of high-flowing air and delivers the highest power gains in most cases. This media is perfect for street and/or track use. Its inverted top makes for more filter surface area, resulting in longer service intervals.