We recommend this larger-capacity 6-gallon carboy for use as a secondary fermenter , especially when brewing lagers or high-gravity beers. It can also be used as a primary fermenter for 3-gallon batches of wine. Glass carboys are great for fermenting because they never scratch or break down over time. Plus, glass does not hold odor, which could impact taste. This carboy uses a #6.5 stopper or a small universal carboy bung. Dimensional Shipping Weight applies.