I have a portable concentrator. Started out with tanks. It is MUCH easier with the concentrator. My tans were only lasting for 2 hours set on 2. My concentrator battery lasts for about 4 1/2 hours and if I'm at a place where I can plug it in - even in the car, it saves on the battery. I love it and consider it well worth the money spent on it. It provides you with so much more freedom every day and helps with the efforts of staying as active as you can be.

P.S You can buy them second hand and nothing wrong with that, as long as you first have the machine checked out and serviced by the manufacture, you can save money by doing this, ....just be careful and check everything out properly first before you hand over your hard earned cash.

I have a large concentrator at home and run at 3 liters continuous flow. I have a portable concentrator (POC), an AirSep, that I rent from Lincare along with my big concentrator. The portable only goes to 3 liters and it is pulse flow. It is airline approved and with the battery belt, I can get about 4-41/2 hours. The length of time depends on how many liters you use. It can be plugged into the car or any outlet, too. With my insurance, I pay $32.54/month for both. This POC is the easiest for me to carry around, and it fits in the basket of my walker when I use that. Just type in POC and you will see all the types.
Hope this helps.

I think the inogen 3 is the best way to go Im glad I did . I nead it just for when I walk .and sometime at night .

I purchased the Inogen One G3 Oxygen System. It was expensive but it sure makes a difference getting around. It's pulse activated and I set it on 1 or 2 depending on what I'm doing. No more tanks, just plug it in to charge the battery