This is one very handy device! It's a standard #6.5 bung for use on a typical carboy. It employs a 14 inch long thermo-well that you can insert a fridge controller probe or thermocouple of your choice. It also has a hole for an air lock. How can life get better than this!
Inside diameter of the well is 0.25 inches. To be used with the Ranco Controller, LOVE SS probe or other 0.25in probe. The Johnson Controls probe does not fit the well.