This W1209 is a low cost yet highly functional thermostat controller with a clear acrylic plastic enclosure. This module intelligently controls power to most types of electrical devices based on the temperature sensed by the included high accuracy NTC remote temperature sensor.
The cooler, heater or fan is connected to a power supply through the relay contacts K0 and K1, and the temperature on/off setpoints are programmed into the W1209 using the onboard Set, Increase and Decrease buttons and display. The relay contacts are then open and closed, acting as a power switch for the cooler/heater, based on the temperature measured by the NTC temperature sensor (included with the module) and the setpoints programmed into the W1209 controller.
Although this module has an embedded microcontroller, no programming knowledge is required. 3 tactile switches allow for configuring various parameters including on & off trigger temperatures. The on-board relay can switch up to a maximum of 20A at 14V DC, 16A at 24V DC, or 7A at 125V AC. The current temperature is displayed in degrees Centigrade via its 3 digit seven segment display and the current relay state by an on board LED.
Specifications:
Temperature Control Range: -50 ~ 110 C
Resolution at -9.9 to 99.9: 0.1 C
Resolution at all other temperatures: 1 C
Measurement Accuracy: 0.1 C
Control Accuracy: 0.1 C
Refresh Rate: 0.5 Seconds
Input Power (DC): 12V
Measuring Input: NTC (10K 0.5%)
Waterproof Sensor: 0.5M cable
Output: 1 Channel Relay Output, Capacity: 20A at 14V DC, 16A at 24V DC, 7A at 125V AC
Includes a Clear Acrylic Case (Box) with mounting screws (assembly required)

Dimensions:
W1209 Board (LxWxH): 48mm x 40mm x 14mm (1.9" x 1.6" x 0.6")
Case (Assembled L x W x H): 59mm x 51mm x 18mm (2.3" x 2.0" x 0.71")