... Type , Pre-Wired Type , Sensing Distance 4m , NPN Transistor OutputE3Z-R61 2M Retroreflective Type , Pre-Wired Type , ... Sensing Distance 4m , NPN Transistor OutputE3Z-R61 5M Retroreflective Type , Pre-Wired Type , ... Sensing Distance 4m , NPN Transistor OutputE3Z-R61K 2M Retroreflective Type , Pre-Wired Type , ...