This optical reflective sensor is used to detect objects when held near a white surface. This sensor includes a Infrared LED and Light Sensor. Normally, the light sensor cannot see the light from the LED until held near a light surface. This sensor can be used to detect light or dark proximity to objects. This sensor is also ideal for detecting a rotating wheel, a moving conveyor, or other proximity detection applications. This sensor has 2 wires for the LED and 2 wires for the light sensor. Includes 18″ cable for easy wiring. This sensor works great with Fusion or Reactor series controllers, allowing relay activation when light is detected.