It is the Chevrolet wheel well opening molding that accents the wheels of your car or truck. When new, this usually chrome colored part helps to improve the looks of your vehicle to others. The problem is that over time debris from the road and other places come in contact with this thin piece of metal or plastic. With each collision this part has with another object, a dent or crack is created. Over time the wheel well opening molding will appear to be unsightly and replacement is preferred by most Chevrolet owners. They are also known for rusting due to the conditions and treatments on the roads, mainly salt in the winter time. On most Chevrolets there are 4 wheel well opening moldings that come standard with the car or truck when it is new. This makes it possible for this shiny piece of trim to accent each wheel of the vehicle. While it will not improve the performance of your vehicle, they sure do make the car or truck look better. Each of the Chevrolet wheel opening moldings is made for a specific model and wheel opening. They cannot be interchanged because of the curvature of each one and their lengths. If replacing just one wheel molding, replacement is simple. If you have purchased a set of the wheel well opening moldings for your Chevrolet, then remove only one of the old ones at a time and match them up to one of the new ones in the set you just purchased. By replacing one at a time the owner of the vehicle can accomplish this cosmetic procedure themselves with an end result of their vehicle looking like new again.