[Lauren]

I have an Inogen One G5 portable concentrator that goes to 5 liters on demand, not continuous flow. The double battery gives you at least 8 hours on 3 liters, but it is HEAVY and kind of defeats the purpose. Single battery is lighter, but on 3 liters it gives you maybe 4 hours. I have my Inogen One G4 for work since I only have to do short walks and can sit a lot, but it only goes to setting 3. This setting in not the same as liters, FYI.