Therapeutic apparatus for controlling and/or delivering gas such as air and/or oxygen to subject, apparatus including Nasal Positive Air Pressure Devices, Continuous Positive Pressure Devices, ventilator and respiratory support devices, apparatus for diagnosing, monitoring, storing, analysing and/or communicating medical data, patient nasal and full face mask devices, including mask devices with in-built sensors, electrodes and electronics and processing capabilities; scientific instrumentation and electronic apparatus for medical use, medical apparatus, patient monitoring, analysing and/or recording apparatus, apparatus for investigating, monitoring, diagnosing and/or recording sleep, sleep related and respiratory disorders, respiratory function and respiration including portable monitoring apparatus, apparatus for monitoring and/or displaying graphical and/or other data, including plotters and display monitors for the above, parts and accessories thereof and therefor