Cask strength. What is a cask? It's a barrel that you put your whiskey into to let it sit and mature. Wood acts like a filter. Most whiskeys are barrel aged because of the brown color. It gives them sweetness. It gives them notes of vanilla and other delicious aromatics. But to be cask strength, generally speaking, it's going to come directly from the barrel to the bottle without being watered down to proof. So, this whiskey is 40% alcohol by volume and that's how it came out the barrels in which it was aged. Put directly in the bottle. It's going to be higher proof. It's going to be more concentrated flavor. You can water it down a little bit to sort of let it spread out so you get more of the... it takes a little while longer to cross your palette. But, generally, the cask strength liquor is going to be much stronger and much more concentrated in its flavor. That's what it means to be cask strength.