Door brace for use with door stabilizer (sold separately) MS304-00001 Increasing the spot and rigidity in racing cars is able to obtain sharp handling, and to prevent damage caused by twisting the vehicle, each part such as the foot area is properly functioning, but it can also be used in passenger cars, and is especially easy to use by reinforcing the door part to achieve a silence and linear responsiveness. We recommend using this product with a door brace.