Many claim that the Glenfiddich 15 is the best edition of the Glenfiddich brand. The whiskey was aged in American bourbon barrels, Portuguese sherry barrels, and virgin oak barrels. Then the whiskey was married using the Solera method, which provides the whiskey with flavors of sweet sherry and a guaranteed and uniform quality in each and every bottle. The production and aging methods of the Glenfiddich 15 year old are the first of their kind in the world. The writing "Solera" in the name of the whiskey marks the aging method of the Spanish sherry, where in each stage a younger beverage is transferred into a barrels that already contains aged beverage. Aged in European oak sherry casks and new oak casks, the whisky is mellowed in our unique Solera Vat, a large oak tun inspired by the sherry bodegas of Spain and Portugal.