Foam density is the most critical indicator of quality and durability. For high-end markets, prioritize high-density foam (≥30kg/m³) as it offers better resilience and a longer lifespan. For budget-conscious markets, medium density (20-25kg/m³) is standard. Hardness (measured in ILD/IFD) should be selected based on target ergonomics; firm foam is preferred for orthopedic support, while soft memory foam is ideal for pressure relief layers. Always request a technical data sheet to verify these parameters.