Calendar function and more intuitive master of time. Button with back-light for clear and intuitive function display. Power-off alarm function. Function of releasing anion. Heat protector equipped in the compressor. Nebulization function (for models with nebulization functions). Oxygen concentration monitoring and alarming. Maxmum flow:5L/min Oxygen concentration:≥90%,when the oxygen flow is 0.5L/min-5L/min Noise:≤60dB(A)Oxygen concentrator introduction: Oxygen concentrator is a device that extracts oxygen from atmosphric air.Oxygen concentrators  could be applied widely in the hospitals or clinics at all different level,clinics,health centers and family nursing,health care for the old person, mental workers and students,etc .The oxyegen concentrator is suitable for 1 patient.