As much as aeration is good for wine, too much oxygen, or prolonged exposure to oxygen, is what starts to make wine turn. Enter The AntiOx Carbon Filter Wine Stopper, a patented system that stops too much interaction between wine and oxygen. The silicone based stopper has an active carbon filter inside. A product of Spain and endorsed by the Spanish Academy of Sommeliers, the stopper also has a day marker. Simply twist the ring to mark the day (1-31) you opened the wine. Pro tip: once a bottle has been corked it should always be stored in an upright position! 1 7/8" by 1 1/2" in diameter. Imprinting not available.