Mould nozzles provide advantages due to the fact that the melt injection gats and the gas injection point do not have to be at the same location. Because of this, several gas introduction points may be arranged on the mould piece to meet specific requirements. Thus, the separate can gas runners gas be controlled differently, allowing special requirements to be fulfilled. Mould nozzles are thus distinguished by their great flexibility in planning and in possible mould modifications. With regard to the manner of installation, a distinction is made between fixed mould nozzles.