When sourcing a used 40 High Cube (HQ) container, you must verify the external dimensions (12.19m x 2.44m x 2.89m) to ensure it meets the extra foot of height compared to standard units. Check for Corten Steel construction, which provides superior atmospheric corrosion resistance. Inspect the floor integrity, ensuring the 28mm marine plywood is intact and free of oil stains or chemical odors. Finally, confirm the maximum payload capacity (approx. 26,000kg - 28,000kg) to ensure it meets your cargo or structural needs.