OPB700 and OPB700ALZ series of sensors from Optek consist of an infrared emitting diode and an NPN silicon phototransistor, mounted side-by-side on converging optical axes in a black plastic housing. OPB701 and OPB701ALZ sensors consist of an infrared emitting diode and an NPN silicon photodarlington, and also mounted side-by-side on converging optical axes in a cost-effective black plastic housing. The interconnect wires for these devices are UL approved #26 AWG, with PTFE- insulation, stripped & tinned. The OPB700 and OPB701 have 4 Inch (101 mm) wire length while the OPB700ALZ & OPB701ALZ have 18 Inch (457 mm) wire length. Series = OPB701 Minimum Operating Temperature = -40°C Mounting Type = Free Hanging Maximum Operating Temperature = +100°C