Sorry I wasn't clearer. You plug the controller into the wall outlet, plug the cooker and the sensor into the controller and put the sensor in the pot. Turn the pot's heat to high and the controller regulates the heat by turning the pot on and off. The name of the company is actually Auberin Instruments. They send a cd with three pdf files to read or print about the controller. I still need to "tune" mine to the pot/cooker I will be using. I have an electric pressure cooker with the heating element sealed in the bottom that's larger and deeper than my slow cooker - I'm going to experiment with that. They recommend using a pot that heats from the bottom, not the sides, to get better convection currents, so you don't have to stir the water.
FYI - to pasteurize an in-shell egg (size unlisted) put it in a 135 degree (F) water bath for at least 1 hour and 15 minutes. For the "perfect egg" cook at 148 degrees for 45 minutes to no more than 1 hour. Again, no size listed.