I have an Inogen G5. Expensive, but has a big battery and can go out for 5 hours at a time. They stand behind there guarantee and replace it 24 hrs if you have a problem.

I even use it on trips, just plug it in and you can use it all night. Plus the smart technology it even recognizes when you don't take a breath.

I'm happy with mine.

Go to this website to get a complete rundown on POCs and what they can do and not do: www.runningonair.org/pocs All the information you need is there. Using the chart, find the one you're interested in and go from there. Most medically approved POCs are pretty expensive: $3,000 - $4000.

I have an Inogen One G5. It helps but not like our concentrators. The portables are pulse which means you get a burst of oxygen. You'll need a prescription from your doctor. Talk to your insurance company as they will be billed. Mine is rented and my insurance pays for it. Good luck!