The classic closure for champagne is a special cork which, due to the high carbon dioxide pressure, has a larger volume/diameter than that for still wines. The cork is secured by means of an agraffe. The small metal capsules attached to the cork are a sought-after collector's item for fans of placomusophilia. The company ALCAN developed a special closure called MAESTRO with the champagne house Duval-Leroy, which was presented in mid-2009.
Serious sources on the internet are rare - and Wine lexicon from wein.plus is one such source. When researching for my articles, I regularly consult the wein.plus encyclopaedia. There I get reliable and detailed information.Thomas Götz
Weinberater, Weinblogger und Journalist; Schwendi