It is exceptionally useful during the start of fermentation when the lag between ambient temperature in the refrigerator and actual temperature in the carboy can vary greatly. Now you can keep your beer or wine within one degree of the set point on your digital controller.
The stopper has two holes measuring 3/8" and 1/4". Measures 14" from the bottom of the stopper to the end of the thermowell.
Designed to fit either 3, 5, 6, or 6.5 gallon glass carboys or any other similarly sized opening hole. The unit comes with a 15" stainless steel thermowell and a #6.5 stopper.