Cao Gang, manager of TSL agricultural technology company, checks the jars in storage in Tongguan town of Changsha, capital of central China's Hunan Province, Dec. 19, 2018. The company produces pickled vegetables with "old jar vegetables" skill, traditional processes inherited from Guangxu Period (1875-1908) of Qing dynasty. The key code of the skill lies in the old jars of Tongguan town, a famous pottery producing area in history. (Xinhua/Li Ga)