Review on 🌡️ HiLetgo 2pcs W1209 12V DC Digital Temperature Controller Board Micro Digital Thermostat -50-110°C Electronic Temp Control Module Switch with 10A Relay and Waterproof by Nathan Tsugawa

The only thing that could have improved these devices would be to include basic instructions in the box. Fortunately, you can find connection instructions and function descriptions on the Internet. Note. I've found some instructions that suggest that the load's positive and negative wires should be connected to K0 and K1, respectively. That's wrong - at least for the device I connected. K0 is positive with respect to the load; K1 plus from the power supply; +12V plus from the power pack; GRND is negative of power supply. You also have a negative signal from your power supply to your load. Press and hold the Set button for 5 or 6 seconds to enter programming mode. With P0 you switch from cooling mode to heating mode. I think Revain's product description covers everything else.