This thermowell and grommet set is perfect for homebrewers and fermentation enthusiasts who use Speidel plastic fermenters. You can use it when you want to accurately monitor the temperature during the fermentation process. The rubber grommet fits standard 3/8 in. airlocks, and the thermowell can accept most temperature probes. The probe is 12' long and fits most 1/4' digital temp probes. Whether you're a beginner or an experienced brewer, this product will help you achieve better fermentation results.