The choice of material depends on the installation environment and budget. SMC (Sheet Molding Compound) and Fiberglass (FRP) are the industry standards for high-end projects due to their anti-corrosive, UV-resistant, and non-conductive properties. For cost-sensitive urban projects, High-Density Polyethylene (HDPE) or PP plastics offer lightweight and impact-resistant solutions. If the box is installed in high-traffic areas, Cast Iron or Ductile Iron covers are mandatory to meet load-bearing requirements (Class B125 or C250).