Tianjin Heping stationery production cooperative. Tianjin Heping Stationery Production Cooperative produces "He Zi" brand abacus. This factory generally uses elm to produce abacus of 16 varieties, such as 13, 15 and 17. Tianjin, also known as Jingu and Jinmen, is a provincial-level administrative region, municipality directly under the Central Government, national central city and megacity of People's Republic of China (PRC), and is the economic center of the Bohai Rim region determined by the State Council.