This Spectre Intake Coupler Reducer is designed to connect a 4 inch outside diameter component or air intake tube with a 3 inch outside diameter component or intake tube. This intake coupler is 3-1/2 inches in length and made from black PVC and comes complete with 2 stainless steel worm gear hose clamps. Not suitable to be installed on pressurized components such as turbocharger or supercharger outlets.