[Closed] Beer at 41% abv - how can this be?

Brew Dog's Sink The Biskmarck is said to be a pale ale but it is 41% abv which is spirit strength. How is this level of alcohol content achieved without distilling? I always thought drinks passed into a different genre at a certain percentage - beers become barley wines, wines become port etc.. I obviously know nothing.

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£40 a bottle and currently out of stock 😯