The large lid allows for easy filling and makes hop or oak additions a breeze. The smooth sides are fantastic for sanitization – no ribs or texture to collect yeast or bacteria. The 6 gallon size is great for most fermentations, and the larger 7 gallon is available for even bigger beers. The punted bottom allows sediment to collect to the sides so that you can siphon liquid from the center. Because they are made from virgin PET plastic they nearly unbreakable and a lot safer than similar glass carboys. Also notice the conical top which reduces surface area if you plan to store beer or wine long term.