Thaum lub Yim Hli, qhov kev loj hlob ntawm kev lag luam steel qis qis qis, cuam tshuam los ntawm kev loj hlob ntawm cov khoom lag luam steel thiab kev hloov kho dua tshiab, steel nqi poob rau lub hli.Nyob rau lub Cuaj Hli, raws li tus nqi ntawm cov roj nyoos nce, cov nqi steel tau rov qab los, xav tias yuav lig yuav tseem qhia qhov hloov pauv me me.