Here is another portable oxygen machine for the elderly and people with breathing issues. The AUPORO Oxygen Machine has a flow rate of 1-6L/min with adjustable concentration of 30 to 90%. It weighs only 5.2kg, so you can easily take it around.
The AUPORO MAFO1 Oxygen Concentrator has a noise rating of 48dB. It comes with a large color LED screen and a convenient timer function.