On the end of many wings you will see vertical plates. These vertical plates, which we call ”end plates” (some people call them “end fences”) are used to help keep the air from spilling off the ends of wings and causing loss of downforce and wing efficiency. “Fences” are vertical plates usually in the middle of a wing and its purpose is to help straighten out the air and consistently generate downforce when a car is in a sideways or “yaw” position. Many rally car wings will incorporate fences to help generate continuous down force when the car is sideways.