This International Standard concerns pin-index yoke-type valve connections for small medical gas cylinders, with a maximum working pressure (filling pressure at 15 °C) of 200 bar. This type of connection is typically used for small cylinders (5 l or below). In some cases, it may be used for larger cylinders. In this latter case, consideration shall be given to the need for valve protection. It specifies: basic dimensions; requirements for alternative designs of the yoke-type valve connections; dimensions and positions for the holes and pins for the outlet connections. It also specifies the dimensions and positions for the holes and pins for the outlet connections for the gases and gas mixtures given in Table 1. This International Standard applies to small medical gas cylinders used for patient care, including therapeutic, diagnostic and prophylactic applications, in hospitals and for emergency treatment.