Ultra compact and easy to install PWM (Pulse Width Modulation) Fan controller allows for soft start (1/2 speed) ramping the fan up to full speed until the coolant temperature drops 20 degrees. Built in potentiometer allows you to dial up start temp. Easily mounts to your core support or other metal surface. Controls (1) one fan with up to 225 watt motor. Includes (1) temperature sensor (1/8 in. NPT) and adapter to go into 1/2 in. NPT threaded water jacket inserts.