Reliance 401 Series, 2" Shank, Honeywell Electronic Propane Gas Control Valve, Thermostat Powered By 750 Millivolt Generator, Noticeable Red Led Indicator Light Blinks 1 Time At 3 Second Intervals During Normal Operation, Increased Temperature Control & Accuracy, Integral Spark Igniter, Fits Reliance Standard 400 Natural Gas Water Heaters With Honeywell Control.