How Does It Work!? sparkling wine stopper is smarter than your average stopper. The seal uses a simple but brilliant physics principle (Pascal's Law). As pressure builds inside the bottle, the plastic nipple expands outward, creating a bubble-tight seal. Lay your bottle flat, or stand it upright and the seal works the same. BPA and Phthalate Free.Fits All Standard Bottle Necks The shape of the bottle can be anything - if the neck is a standard 750ml Champagne or Sparkling Wine bottle neck (and we all know what that looks like), then this Champagne preserver will fit. It can be used for Prosecco, Cava, some Magnum and 187ml bottles, and many large format beer or cider bottles. Easy To Use Unlike the outdated style of Champagne bottle stoppers (the exploding spring-loaded type), our Champagne Saver is easy and fast. Simply press the cap down (the seal does the rest of the work for you), then lock with the stainless steel safety clip. Its easy to release, even with arthritic hands! And, the key to max fizz is to seal your bottle right away, and keep it ice cold.