ISO 1135-4:2015 specifies requirements for single use transfusion gravity sets for medical use in order to ensure their compatibility with containers for blood and blood components as well as with intravenous equipment. Secondary aims of ISO 1135-4:2015 are to provide guidance on specifications relating to the quality and performance of materials used in transfusion sets, to present designations for transfusion set components, and to ensure the compatibility of sets with a range of cellular and plasma blood components. In some countries, the national pharmacopoeia or other national regulations are legally binding and take precedence over ISO 1135-4:2015.