The new CR0 polarized retro-reflection photoelectric array is an optoelectronic device that can be used to detect the presence of any object that obscures or reduces the light intensity of light beam returning from reflector. This reflex sensor provides barrier-like detection performance, with the advantage over traditional area sensors of having four emitters and three receivers in the same body and a single connection cable. These features result in simplification and reduction of costs and installation time. It is sufficient, in fact, to connect an M12 cable to a standard 4-pin connector and to teach-in by pressing the only button on the sensor.