To create The Balvenie PortWood 21 year old single malt whisky, a marriage of rare Balvenie is transferred to port casks, or pipes, which have held fine port wines. Here it is sampled regularly by The Balvenie Malt Master David C. Stewart MBE to ensure that just the right amount of character is imparted by the port casks, enhancing and developing the single malt whilst preserving its original characteristics. Considered by many to be David's finest creation, this whisky is one of his proudest achievements and has won an array of highly coveted industry awards since its release in 1996. In duty free, The Balvenie PortWood Aged 21 Years is non chill-filtered and bottled at a higher strength of 47.6% abv.