Omron E3Z-R81 Retroreflective Photo-electric Sensor Pre-Wired Type , Sensing Distance 4m , PNP Transistor ... Output E3Z-R81, E3Z Omron E3Z-R81 Retroreflective Photo-electric SensorPre-Wired Type , Sensing Distance 4m , PNP Transistor OutputE3Z ... .1 to 3m , PNP Transistor Output Omron E3Z-R81 Retroreflective Photo-electric Sensor