SBE Solar Tech Digital Differential Thermostat w/Pwr Supply and Solid State Relay - SPDT relay output. This means you have "normally open" and "normally closed" output - LCD display of current sensor temperatures, current differential, and differential setpoint. Freeze protection, will not trip relay if either of the sensors are disconnected, or below freezing - User selectable Celsius/Fahrenheit readout. - Will run from just about any "wall wart" type power supply. (not included)