From The Official Website

Convention said blended malts should mature in pre-used bourbon casks. But where’s the fun in following convention?

Instead, we extra-matured our unique blend of the world’s finest single malts in first-fill sherry casks. Naked casks we called them, as they’d never held whisky before.

This liberating leap into the unknown didn’t just work, it changed the possibilities of whisky enjoyment forever.