The Q45BB6 series miniature DC Photoelectric Sensor that are totally self-contained with powerful visible red sensing beam simplify setup and alignment. Sensor include self-diagnostic circuitry and one output may be used as a marginal signal alarm. The sensor features LED indications for Power ON, Output Status (including overload condition), Alignment and Marginal Signal. The standard Q45 is a basic ON-OFF Sensor that makes your job easier with a host of advanced standard features including three LED’s for "power", "signal" and "output" indication, plus patented diagnostics that alert you of output overloads, output short circuits and marginal sensing conditions. The Q45 even measures exact signal strength with Banner’s exclusive AID™ system, so you will be better informed on how your sensors are performing.