This part of ISO 5366 specifies requirements for tracheostomy tubes made of plastics materials and/or rubber having inside diameters of 6,5 mm or greater. Such tubes are primarily designed for patients who require anaesthesia, artificial ventilation or other respiratory support, but need not be restricted to these uses. This part of ISO 5366 is not applicable to specialized tubes, and does not address flammability of tracheostomy tubes.