The RVS-112-W Vehicle Reversing Aid is an automatic backup alert system that warns drivers of potential obstacles behind their vehicle - up to 8ft away! The cables, control module, and sensors are all waterproof, allowing you to install all components outside the vehicle. Using ultrasonic echo location sonar technology the system is activated when the driver engages reverse gear. A 4 zone variable audio pulse alerts the driver of potential obstacles. The audio pulse intensity increases and the audio frequency changes as the vehicle backs closer to the obstacle. As with all sensing systems there are blind areas in the sensing patterns due to the cone or triangular nature in the way the sonar pulse is emitted. Whenever an object moves from a covered area and into one of these blind areas a special warning alert message and a very loud tone will be transmitted twice or until the operator takes the vehicle out of reverse. This is especially helpful for detecting moving objects such as a pedestrian, an animal, a forklift or other moving vehicles that may be behind your vehicle and in harms way. These intelligent sensors automatically ignore stationary, permanent objects, such as truck steps, up to 30cm away. This gives you flexibility for installation location. ***Note: In addition to ground and reverse (trigger) power, you must also connect the RVS-112-W to a constant power source. ***The RVS-112-W only works with certain model numbers, please call us before ordering to make sure its compatible. ***Please note that the audio alarms will only work when using a monitor equipped with a speaker. ***Note: Please install interface of module towards the ground to reduce dust during use.