Lochinvar & A.O. Smith 100208325 Indicator Light 321894 708 Thermal Resistance: High grade synthetic material Thermal Resistance: High grade synthetic material provides a gas tight seal that resists degradation from frequent heating and cooling cycles The Johnson Controls A28GJ 33 Temperature Control is a heavy duty two stage mechanical thermostat engineered for precise thermal management in commercial HVACR and industrial process applications Key Benefits Instant Diagnostics: Provides a clear green visual signal to confirm the control board is energized or the unit is in a specific stage of operation Operating on a 24V AC DC control signal