K&N Universal Air Filter - Round Tapered 3.5in Flange ID / 5.5in Base OD / 4.5in Top OD / 6.5in HThe RP 4630 Universal Air Filter is constructed from an oiled cotton filter media. It comes with a K&N embossed carbon fiber top for strength and durability. The carbon fiber element adds to the light weight design and gives this filter a smooth glass like finish. The RP 4630 is a clamp on filter that has an inside flange diameter of 3 1 2 inches and a flange length of 1 1 4 inches. The base diameter is 5 1 2 inches, the top diameter is 4 1 2 inches