Use this rear diffuser when you want to enhance the look of your 2018 - 2019 Audi S4. It's perfect for Audi S4 owners who love to customize their cars. Made of FRP material, it provides a good balance of weight and strength. Although the exact weight and size aren't specified here, you can expect it to fit well on your Audi S4 as it's designed for this specific model and year range.