When sourcing EPS balls, the most critical factor is density (measured in kg/m³ or g/L), as it determines the structural strength and buoyancy. For construction or insulation, high-density balls are required for compressive strength. For bean bag fillers or packaging, lower density is preferred for cost-efficiency and softness. Additionally, specify the bead diameter (e.g., 1-3mm, 3-5mm) to ensure compatibility with your filling equipment or molding process. Ensure the product has a low residual pentane content to prevent shrinkage after purchase.