When sourcing assembled shelves, the most critical factor is the Load Capacity per Layer, which must be clearly defined (e.g., Light-duty 100kg, Medium-duty 200-500kg, or Heavy-duty >1000kg). You should prioritize Cold-Rolled Steel (SPCC) for the frame to ensure structural integrity. Additionally, verify the Surface Treatment, such as Electrostatic Powder Coating, which provides essential corrosion resistance and scratch durability. For high-moisture environments, Galvanized Steel or Stainless Steel (304/316) is mandatory to prevent rust.