The 15 Year Old's distinctive character is the result of selective maturation; a proportion of the spirit is matured in a selection of French Oak casks for a limited period, so as not to overpower the final result. The Glenlivet was one of the first distilleries to use French Oak in the whisky making process, a technique that has since been imitated by many others. Limousin Oak, which is cut in the Dordogne region of France, is often used to mature fine wines and cognacs. In the case of The Glenlivet, its low density allows the spirit to penetrate deep into the wood, imparting the expression's distinctive spiciness. The French Oak also increases the intensity of the whisky, resulting in a richer and creamier finish.