Imogene has a lightweight one that is about 2. 1/2 lbs. my portable is about 5 lbs.

There is one machine that is lighter, the Inogen G 4 or Oxygo Fit. It weighs three pounds, and will last, according to Ryan Diesem who tests these machines, for 2.3 hours. However, and this is a BIG however, it only produces a max of .63 LPM. So it's probable that it won't meet her oxygen needs because it won't produce enough for her. At 5 pounds, the Oxygo Fit she has is very light weight. I think they have a cart that you can use. Before you buy, she needs to use it to see if it will keep her oxygenated. It's an expensive mistake to make.

I finally bought a concentrator for my downstairs, was a little spendy but now I have oxygen on both floors. You can buy a used one at a pretty reasonable cost.

My portable Concentrator only lasts two hours...have two of them and I fill them myself...My insurance Co. is fighting my to getting the Imogene ( cheaper kind) my doctor ordered. They want me to exchange the two Portables I have and I can't due to the way my home is arranged, have basement and 2nd floors also. I need them for each floor...The large Concentrator line does not reach everywhere, and I tend to trip on the line...It's crazy...I'm stuck at home, more than five years now...With the Imogene type concentrators I can go out visiting and plug it in their home...also use it in the car...I will continue to fight this...

Thank you so much. She is 85 years old and tiny. I just want to get the best concentrator for her that she can handle easily.