This device is a 4 wire temperature controlled fan speed regulator that allows for automatic or manual of fan speed bases on temperature readings low temperature shutdown of fan within 3A (directly turn off the fan power), supporting reverse timing fan, and display of fan speed at 10000 rpm Systems help maintain great cooling and energy efficiency by increasing fan speed as temperatures rise and reducing speed when cooling demand is lower It features a digital display showing both current temperature and the fan ’ s rotational speed in RPM (revolutions per minutes Note: This controller only control the fan speed controlled by a four wire standard signals, with a signals specification of 25KHz 5V