Grolsch Gaskets Silicone Seals For Swing Top Bottles by Yuwanting (red, 40)

These work great on my authentic Grolsh botles. You have to work them a bit to get a proper fit, but once you do, they work fine, tight seal. They cover the whole stopper, not just a ring. They also fit a generic flask that has a plastic stopper.

These really seal. The difference in carbonation was night and day compared to the original washer style seals.

Had some swing top bottles that the rubber had come apart. These fit perfectly and no leaks.

Works good and fits great.

These are awesome for fermented beverages. Air tight seal and easy to clean.

Great item

Pretty good Chinese product, on first inspection the material seems tough and durable. A little thicker than the standard Grolsch washer/seal so the lid snaps a little tighter on the Grolsch bottles. These also fit the Bormioli Rocco Swing top bottle we keep olive oil in. The complete cap design instead of a washer with a hole in it makes for a cleaner reusable seal.

If your homemade Kombucha isn't fermenting to a fizz anymore, change the bottle seals. These worked great for me.