The illustration shows the "REX-C100" temperature controller. Quality brand, lots of documentation available online. My device came with a clone of this controller "RRKKCC". My temp isn't 40 degrees and if it was a rex you could access the menu and calibrate it. This menu has a different structure and I can't find any instructions for it. Everything I find online speaks ill of this PID controller. Also note that there is a small ledge in the center where the top board is machined, preventing the PCB from sitting flat on it. i will return it