The EL-1500-L is a sensor replacement kit for Optima ES-S style flushometers. The kit contains the Sloan water closet sensor. This sensor can only be used on Sloan Optima ES-S style flushometers. The EL-1500-L sensor is intended for flushometers operating with a 24V electrical supply.All of Sloan’s sensor flushometer models operate by means of infrared sensor. In this application the sensor emits a beam of infrared light, when a user steps in front of the water closet or urinal, that infrared light ‘bounces’ off the user reflecting back to an infrared detector in the sensor. Infrared light, like visible light, will reflect back with greater intensity off brighter and more reflective surfaces. Sloan’s optical engineers understand this and Sloan designs its sensor to work within a general window of reflective environments typically found in a public restroom.