This standard applies to breathing sets, breathing tubes, and connectors that are intended to be used with anaesthetic equipment, respiratory equipment, humidifiers and nebulizers. It specifies general design requirements but also performance requirements regarding leakage, flow resistance and compliance. The performance requirements are supplemented with the required test methods. In addition, the standard includes requirements for packaging, labelling and marking as well as information to be provided by the manufacturer. In comparison with the standard DIN EN 12342:2010-01 "Breathing tubes intended for use with anaesthetic apparatus and ventilators", German version EN 12342:1998+A1:2009, the scope has been extended to cover breathing sets, which means complete assemblies of breathing tubes, connectors and components that form the inspiratory and expiratory limbs of the gas pathways of an anaesthetic or ventilator breathing system between the ventilator and the patient's airway device. The standard also considers coaxial breathing tubes. The basic requirements and test methods have been extended and revised accordingly. The standard has been prepared by Technical Committee CEN/TC 215 "Respiratory and anaesthetic equipment" (secretariat: BSI, United Kingdom) in collaboration with Technical Committee ISO/TC 121 "Anaesthetic and respiratory equipment". The responsible German body involved in its preparation was Working Committee NA 053-03-02 AA "Medizinprodukte für das Atemwegssystem" ("Airways and related equipment") of the DIN Standards Committee Rescue Services and Hospital (NARK).