Nai lao (or suān nǎi) is prepared by heating milk and adding sugar to it. Two types of nuts mixed with raisins and rice wine made from glutinous rice are poured in and thoroughly stirred. A special device called lào tǒng 酪桶 (or yogurt barrel) is used during production. A lào tǒng contains a heat chamber in the center, providing the heat needed for cooking. The milk is mixed with rice wine and honey or sugar and is rapidly poured into fifty small bowls. The bowls are then stacked along the inner wall of the yogurt barrel, heated for about thirty minutes, and later cooled.