APR 2018-2021 Subaru STI Only Brake Cooling Kit***Fits 2018 2021 Subaru STI ONLY*** 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, the APR Brake Cooling Ducts will help