JEGS Variable Speed Fan Controller is designed with pulse width modulation technology allowing you to have greater control over engine temperature. This fan controller adjusts initial temperature when your fan turns on to your normal operating temperature. The Fan Then Starts at 60% power and gradually increases speed to Full Power as the temperature increases. This Soft Start Technology prevents Charging spikes and helps balance the Load on Your Electrical system for longer life. JEGS adjustable fan controller includes color-coded wiring and instructions for a quick and easy installation.