This Cadet R841C1227 is a Low Voltage Mercury Free Thermostat. This thermostat is reliable comfort control. Adjustable heat anticipator provides even control. This thermostat is easy to use. Familiar design and twist to set interaction. This thermostat has a simple user interface. Set temperature and thermometer scales on thermostat face.This thermostat is 1 circuit relay and can go up to 240V. When the heater load is greater than 3,500 watts, a low voltage thermostat with relay is recommended for tighter temperature control. A relay is required and is available for loads up to 5KW and 10KW.