Bushmills 21 Year Old is a marriage of single malts matured for at least 19 years in hand-selected Oloroso sherry butts and bourbon barrels, then finished in Madeira casks for a further two years. This unusually long finishing period allows their single malt to patiently mellow, mature and pick up deeper notes of ripe fruit and dried raisins from the fortified Portuguese wine casks. Bushmills 21 Year Old is only crafted in limited numbers and each bottle is numbered.