These air curtain blockers have been tested in the wind tunnel and proven to provide a few more pounds of front downforce, as well as 6-7% more cooling capacity as measured with pressure probes in front of and behind the oil cooler vs when its open. These results were with stock width wheels, but wider wheels should see better numbers. They are sold as a pair (left and right) and come with hardware. Please note that due to their location in the wheel well, they are not clear coated. They are a raw carbon part as the clear coat would get chipped with stones immediately.