Simple beam. Mirror reflection. For indoor use. Range: up to 5m. The sensor contains the transmitter and the receiver. The transmitter projects the beam towards, which reflects it to the receiver. The protection diagram is established by the beam transmitited to the mirror, and form there to the receiver. When interrupted,the receiver will set up an alarm. Given that the wiring is only made at the end of the sensor, as it contains the transmitter and the receiver, it is only used in places where it is difficult to wire the ends or the sides. The line-up is only made at the end of the detector.