Exceptional Cask Selection Mark IX The top of the range from this coveted distillery is a one-off release for 2019 consisting of rums aged for 14yrs in ex-Bourbon and ex-Sherry casks. Foursquare Rum Distillery Empery is a blend of Pot/Column distilled rum aged for 14 years in ex-Bourbon casks and a portion of Pot Column distilled rum which was aged for 10 years in ex-Bourbon casks and then matured for a further 4 years in ex-Sherry casks.