Open Top Fermenters are a great way to store wine. The tanks are stainless steel which makes them easy to clean. Regardless of the amount of wine put into the tank, the lid is lowered onto the surface of the wine and the pump is used to inflate a bladder that surounds the lid. The wine is then sealed from the outside air. If wine is removed via the spigot, the lid can then be lowered again onto the surface of the wine and the bladder reinflated so that air is excluded.