Tong duck egg is made from the eggs of free range ducks along the Tonghe River in Tanghe county. These duck eggs are big and thin skinned, and the red yolk can be seen through the egg skin.
In 1993, Tanghe Tong Duck Egg Co. legally applied for the brand and trade mark of "Tong". In 2002, the annual yield of Tong duck eggs reached 10 million, with a production value of 8 million yuan ($1.3 million) and tax of 1.21 million.