After drinking a few glasses of a good bottle of wine, these ON/OFF Gard'Vin stoppers from Atelier du Vin are a great way to preserve the rest of your bottle. Along with the ON/OFF Gard'Vin Wine Saver, the ON/OFF Gard'Vin stoppers prevent wine oxydation. The ON/OFF system has a color indicator fitted to the Gard'Vin stopper. It allows you to tell immediatley whether or not your open bottle is protected from the air. Not suitable for sparkling wine.