This intermediate Buon Vino stopper is a convenient replacement for #9.5-#10.5 rubber stoppers, giving you one universal stopper that will provide a snug fit and reliable seal for your BetterBottle PET plastic carboys, no matter what the size. It is drilled for use with an airlock, and features a large lip that prevents it from falling into your carboy.
Note: For glass carboys, a small Buon Vino stopper will be needed.