8050Designed for air intake applications4 inches reduced down to 3.5 inches inside diameterRubber hose molded couplerGreat for DIY racersK&N offers a wide selection of hose in a variety of diameters and lengths for replacement parts and for do-it-yourself racing air intake needs. The K&N 08050 is designed for K&N air intake systems. It has an 4 inch inside diameter that reduces down to 3.5 inches if needed.