韩建河山：主营预应力钢筒混凝土管、钢筋混凝土排水管的生产与销售

Group 1 - The company, Han Jian He Shan, primarily engages in the production and sales of prestressed concrete pipes (PCCP) and reinforced concrete drainage pipes (RCP) [1] - The sales of RCP products in the Hebei region are significant for the company, particularly for urban and residential drainage projects [1] - The revenue contribution from RCP sales in the Hebei region for the years 2022, 2023, and 2024 is projected to be 3.54%, 2.80%, and 1.41% of the company's total revenue, respectively, indicating a declining trend [1]