This is a direct-fit, bolt-on Flex-A-Lite® dual electric-fan system for the 1998-2003 Ford Super Duty truck with the 5.4L or 6.8L gas engine or the 7.3L Power Stroke Diesel. Recover up to 27 horsepower and boost your fuel economy by up to 6 percent by replacing your stock clutch fan assembly with this dual electric fan system. It features two 15-inch S-Blade electric fans and a Flex-A-Lite Variable Speed Controller that varies the fan speed from 60-100 percent, depending on radiator temperature. These powerful fans move up to 6,200 cfm of airflow!