I need only 2 or 3 L when sitting and I turn it up to 5 or 6L when active depending on how active I am. My concentrator is downstairs, that is where I spend most of my time. I sleep with a Cpap machine for sleep apnea but mainly because during my sleep test my oxygen dropped to 74% while sleeping so to keep my level at 92% when I go to bed so it does not drop too far, I need 4L. It is really bad for us to get too much oxygen and have our levels too high so I have to try and walk upstairs on 4L to go to bed and it is so hard. I feel like I will pass out when I get up there. I heard that there is a device you can buy on Amazon and keep it in a arm phone holder so you can change the Liter flow coming from the concentrator without having to go to the concentrator to do it. It is called an air flow oxygen something. I need 6L to walk up stairs but need a way to change it to 4 L when I am up there. Does anyone know of what this gadget is? This is what someone told me to get, I ordered it and could not figure out how it would do the job... https://www.amazon.com/gp/product/B07DNW6JHX/ref=p...