Skunk2's (84-90) millimeter big-bore throttle body cold-air intake coupler allows for easy installation of Skunk2's 2006-2011 Civic Si cold-air intake when using a Pro Series throttle body or similar (also compatible with OEM TL throttle body). Simply replace the cold-air intake system's included silicone coupler with Skunk2's (84-90) millimeter version for a simple, factory-like fit.