The APR Brake Cooling Ducts are aerodynamically-optimized to “funnel in” massive amounts of air. Also known as the venturi effect, when the vehicle speed increases, this funneled-in air increases in both pressure and velocity as it passes from the larger frontal area into the smaller pipe section of the brake duct. When matched with appropriate high-temperature air duct hoses (not included – purchase hoses from your favorite racing-supply shop), the APR Brake Cooling Ducts will help to channel in large volumes of fresh air to help cool down red-hot brake rotors lap after lap on the track.