A solenoid valve is an electrically operated device used to control flow. When the solenoid is not energized, the pilot lights on the knob remain off. As soon as the solenoid valve coil is energized the LED’s will Illuminate.FeaturesEncapsulated high intensity LED pilot lightsThreads into the Solenoid-Tube assembly easilyEasily visible from all anglesHarsh environment compatibleAdaptable to standard encapsulated industrial coilsAC power only115 - 240 V50 - 60 HzO-Ring gasket includedIndependently powered LEDs