Black Bull is still blended to the same formula today as was used in the very beginning, using a large percentage of quality Speyside and Highland malts, matured in sherry and bourbon casks, blended to a high malt to grain ratio, and finally bottled at a robust 50% abv. Black Bull 21 is unfettered by chill filtration, allowing the character of each carefully selected 21 year old whisky to shine through to its full potential, resulting in a unique blend that is outstanding in its field.