The Universal Latch Sensor is a magnet that attaches to an existing latch, and a magnetic sensor that attaches to the inside of an existing door frame. When the door is closed, and the latch is engaged, the magnet comes into proximity with the sensor, sending an electronic signal to your security system. This signal from the ULS can be used in a variety of ways, from integrating security systems, to turning on existing lights inside an enclosure.