The Wine Saver Concerto is a vacuum pump that extracts air from an opened bottle and reseals it with a reusable rubber stopper. Simply place the reusable stopper in the bottle and use the Wine Saver pump to extract the air. A "click" sound from within the pump indicates when you have reached the optimum vacuum level. The vacuum slows down the oxidation process, allowing you to enjoy your wine again at a later date.