"The Balvenie Doublewood is a 12 year old single malt which gains its distinctive character from being matured in two wood types. Over the period of maturation it is transferred from a traditional oak whisky cask to a first fill European oak sherry cask. Each stage lends different qualities to the resulting single malt ~ the traditional casks soften and add character, whilst the sherry wood brings depth and fullness of flavor." -balvenie.com