Knappogue Castle 21 Year Old is a limited-edition single malt Irish whiskey, with only 1,200 bottles produced. First put into casks in 1994 and 1996, this marriage of two single malts – aged 21 and 23 years – is made exclusively from malted barley. Distilled in copper pot stills and matured in B1 bourbon casks, this expression is nonchill filtered and bottled at 92 proof.