The gallon jug brush is just what it sounds like: a brush that is larger than the standard bottle brush, which can be used in cleaning dirt and debris from gallon jugs. That being said, nothing is more useful to the small batch experimental brewer than a gallon jug brush. Many people do small batches of both beer and wine in gallon jugs for the variety, cost saving, and experimentation aspects of brewing and vinting. For these proud zymurgists, we highly recommend a gallon jug brush to keep all your fermentation vessels clean!