From Bruichladdich: "Our Octomore .1 editions are distilled from 100% Scottish barley. In recent years they have been primarily aged only in ex-American oak, in varying percentages of different ex-bourbon and ex-Tennessee whiskey casks. They are the backbone of each new series as they demonstrate the raw character of the clean Octomore spirit balanced with the neutral American oak casks." This was the most heavily peated whisky in the world as of 2015- 167 ppm of phenols. Bruichladdich has released peatier Octomore versions since then.