The Zero/Sports Cool Radiator Shroud Attaches to the top of your radiator and blocks incoming air from escaping around the top of the radiator. Without the shroud, some of the incoming air intended to pass through the radiator can pass through the gap between the top of the radiator and the frame.The Zero/Sports shroud forces that air to pass through the radiator, increasing cooling efficiency and lowering coolant temperatures by 3-5 degrees Celsius. The Zero/Sports Radiator Shroud is the only shroud that also includes foam strips to seal the sides of your radiator to further improve cooling efficiency.