Autotecknic Dry Carbon Intake Air Duct - BMW F80 M3 F82 F83 M4AUTOTECKNIC DRY CARBON INTAKE AIR DUCT F80 M3 F82 F83 M4 Part # BM 0021 CF AutoTecknic Dry Carbon Intake Air Ducts are designed to mount behind the front grills of your F80 M3 and F82 F83 M4 to provide a "ram air" effect by utilizing the air intake motion to increase the static air pressure entering the intake manifold under the bonnet. This creates greater airflow throughout the engine by forcing in increased cooler air, resulting in lower engine