To ensure structural integrity, containers must have a valid CSC (Container Safety Convention) plate, which acts as a safety passport for international shipping. For food-grade or high-end storage, ensure the unit is Wind and Watertight (WWT) and has a Cargo Worthy (CW) status. Check for ISO 1496 compliance, which guarantees the container can withstand the pressures of stacking and sea motion. If sourcing from China, look for suppliers on Made-in-China.com who provide BV (Bureau Veritas) or ABS (American Bureau of Shipping) inspection reports.