Maury is a "vin doux naturel" style created by adding fortifying spirits, such as brandy, to the wine in mid-fermentation. This halts the activities of the wine yeast leaving the wine with "natural" residual sugars. Maury is vinified in a manner similar to port, but initial aging is often conducted in large 25 liter (6.6 US gallon/5.5 imperial gallon) glass jugs known as "bonbonnes", "les dames jeannes" or demi-johns. The wines may also be aged in wood for up to 15 years. The resulting wines vary in depth and concentration.