The Balvenie 21 Year Old Single Barrel Traditional Oak Single Malt Scotch WhiskyThe Balvenie Single Barrel Traditional Oak 21 Year Old is a single malt scotch whisky that has been matured exclusively in a refill American oak cask for at least 21 years. Our Malt Master carefully samples the aged whisky, cask by cask. He will only select single malt characterized by the subtle spices and rich honeyed sweetness he expects from maturation in this type of cask to be bottled as The Balvenie Single Barrel Traditional Oak.