I use an Inogen G5 for flying. It works quite well for that and I can use it for other things as well.

Hi kathi I have a portable o2 machine, (Inogen), love it and use it often I have a charger in the house also one in the car gives me freedom anywhere so if you are thinking of getting one you won't regret it. Ernie

Thank you!!!

I also have an Inogen G5.