One Flex-A-Lite Variable Speed Controller with Electric Fan Relay Kit and Thread-In Temperature Sensor (31163)This variable speed cooling fan controller has a built-in relay function, which means no need for external relaysFlex-A-Lite Variable Speed Control Module includes 1/4-inch NPT threaded temperature probe with 3/8-inch and 1/2-inch thread adapters汽车用品 fan controller starts fans at 60 percent power and increases speed as temperature rises; and runs fans for up to 25 seconds after the vehicle is turned off to remove excess radiator heatThe Flex-A-Lite Variable Speed Controller is the perfect companion to 汽车用品 electric dual-fan systems