Buyers should prioritize Retro-reflectivity Coefficients (R'), typically measured in cd/lx/m². For high-visibility safety applications, ensure the material meets ASTM D4956 or EN 12899-1 standards. The honeycomb structure (micro-prismatic technology) provides superior wide-angle reflectivity compared to glass bead types. Additionally, verify the base material (PVC, PET, or Acrylic); Acrylic-based vinyl offers the best weather resistance and is suitable for long-term outdoor signage, while PVC is more flexible for curved surfaces.