Pork bellies are the underside of the hog, from which bacon is made in the United States (in other parts of the world, bacon is more often made from back and side meats and bacon made from bellies is referred to as streaky or American Style). This cut of meat is enormously popular in Chinese Cuisine where it is generally marinated and cooked as a whole slab . Pork bellies and pork belly futures contracts have been traded on the Chicago Mercantile Exchange since 1961. The unit of trading is 20 tons of frozen, trimmed bellies. Pork bellies can be kept in cold storage for an extended period of time, and generally it is the frozen bellies that are most actively traded. Bellies typically weigh around 13 pounds. Prices vary depending on the amount of inventory in cold storage and the seasonal demand for bacon.