... : international Q235 material, Good elasticity, not deformation, not flagging for life. Add the perfect double galvanized; not rusts, service life ... , heat-resistant, not deformation, no broken. Using life is for 15 years. High compressive capacity: adults can walk random on ... steel ball. Use life is for 14 years. If it damage or leakage in Three years, replacement for free. (Except artificial damage)6 ...