PERFECT FERMENTATION. Proper fermentation temperature is vital for good fermentation. This thermowell allows your temperature probe to be in the perfect position for sterile temperature control.;GREAT COMBO. This #7 stopper include an airlock hole in addition to the thermowell.;COMPATIBLE. Works with most glass carboys and most temperature controllers;Search Amazon for B01IFVSSRM to pair this thermowell with our digital temperature controller;This listing is for the thermowell only. Carboy, heaters, and temperature controller sold separately.