Product review (5 stars): Holding temp as desired
I'm not the smartest guy around, nor do I really want to mess with original manufacturer equipment and controls.  Nor do I want to be drilling holes in a deep freezer, possibly puncturing a cooling coil.  So for someone like me, who is 1) Lazy, and 2) Not knowledgeable enough to be engaging in alterations to mechanical and electrical components, this thing is perfect.

Put the 'bulb' end in the freezer via the gap between the lid and body when opened, hung the controller on the wall with provided hanging chain, and plugged it into the socket and the freezer into the unit.  Set the temp at 40 degrees on the controller dial.  Put a thermometer in the freezer and walked away.  Came back several hours later and it was right on temp.  Continued checking over the next several days and its right where it should be.

Put my kegs in the keezer and I was done.  This thing is perfect for my needs.