B2B buyers must ensure blood bags are made from medical-grade PVC (Polyvinyl Chloride), typically plasticized with DEHP for red blood cell stability, or DEHP-free/Citrate-plasticized materials for sensitive applications. The bags must feature ultra-smooth internal surfaces to prevent platelet activation and include high-quality needles (16G or 17G) with siliconized tips for painless venipuncture. Standard capacities usually range from 250ml to 500ml, and the configuration (Single, Double, Triple, or Quadruple) should be selected based on the required component separation (plasma, platelets, and cryoprecipitate).