This device is not adjustable, comes in increments of 10 degrees C, and has a mechanical switch in it.The device above will do everything that the OP requires at lower cost and a fraction of the effort than most of the other solutions put forward.
I will admit I have only replaced about 3 Klixon sensors in a 40 year career, but I have never repaired the LM723 based thermostat in 37 years of continuous operation, and it is adjustable to a tenth of an F degree.