ONE SINGLE 4 CELL INOGEN BATTERY. Used once for two hours. $150.00
TWO DOUBLE 8 CELL INOGEN BATTERY. One was used for 2.5 hours the other was never used. $250.00 EACH
You may try them out in your machine if you would like to. They are new and I fully guaranty them for 30 days.
I bought the batteries and a few weeks later my oxygen company took the concentrator back and gave my a different brand. Leaving me with brand new Inogen batteries.