Valve/elbow assembly and mask not included — this is the membrane only.
About this part
Full face masks cover both the nose and mouth, so ResMed builds an anti-asphyxia valve (AAV) into the elbow assembly as a safety measure. During normal therapy, pressurized air holds the valve closed so all your air comes from the machine. But if the airflow stops — the machine is switched off, unplugged, or fails — the valve opens automatically, letting you breathe fresh room air rather than rebreathing the carbon dioxide trapped inside a full face mask.