Reliance 401 series, 2" foam insulation requires longer shank Resideo electronic propane gas control valve, thermostat powered by 750 millivolt generator, noticeable led indicator light blinks 1 time at 3 second intervals during normal operation, increased temperature control & accuracy, integral spark igniter, fits reliance standard 401 propane gas water heaters with Resideo control. old part# 9007891