The SIEMENS RAR9 2210 Boiler Flame Detector, commonly referred to as a flame eye or photoresistor flame sensor, is an essential safety component designed for the continuous supervision of oil and gas burners. Utilizing highly responsive photoresistor technology, this detector accurately monitors yellow-burning flames within combustion systems to ensure safe, efficient, and reliable operation. It is specifically engineered to integrate seamlessly with Siemens and Landis+Gyr burner control units. The detector features a durable black cylindrical plastic housing with a ribbed sensor head and a rectangular optical viewing window at the top for optimal light capture. For ease of installation and maintenance, the RAR9 2210 includes an integral mounting flange secured by two fixing screws and a convenient terminal connection slot located directly on the body.