Product details:

Diameter, Stainless Steel Blades/Steel Hub, Each - Keep your engine cool with Perma-Cool! Turbo Flex flex fans pull additional air through the radiator at low rpm when the speed of the vehicle isn't enough to cool the engine's coolant system. At higher rpm, when the vehicle's speed forces ample air through the radiator, the fan blades flatten out, resulting in less power being used to spin the fan. Engine performance and gas mileage are also improved. Flex fans are ideal for applications requiring extra cooling, such as vehicles with turbo or superchargers.