The function of the Big Gulp is to provide additional air to the Roto-fab CAI system (may work with some others) while having the capability of maintaining a functional brake cooling duct. The adjustable feature allows users to direct incoming air to where it is most beneficial, depending on anticipated driving conditions. The Big Gulp is adjusted via the slide lever which extends through the front grill opening for easy manual operation. The "air intake" position channels virtually all of the incoming air to the air intake system. Choose this position for "all out" performance situations such as drag racing when heavy braking is not anticipated. The "brake duct" position provides approximately the same volume of air to the brakes as the stock brake cooling duct while providing additional air to the air intake system. This is possible because the Big Gulp uses the entire available opening in the grill and maintains a larger cross-section than the stock duct. Choose the "brake duct" position for road course type situations or downhill travel where heavy braking is anticipated.