A very limited selection of the Straffe Hendrik Quadrupel production is barrel aged each year in the medieval cellars of the "De Halve Maan brewery". For this special Xmas Blend, the barrel selection is determined by De Halve maan's brew masters, combining Bordeaux, Calvados and Rum barrel-aged Quadrupel with young Quadrupel. This special blend is then refermented in the bottle, allowing for even more complexity, fine effervescence, and an extended shelf life.