They use them to store the malt (similar in vicosity and components to molasses) that is an integral part of brewing beer.
I have sterilized and scrubbed it out several times but it still smells like molasses, which I guess is not a deal-breaker. I was surprised at the filled weight. There was no way I alone could even tip it when full. I would have to use a car or truck, and get a running start. It was very heavy.