My question is with all the technology we have (Can send a singer to outer space, cell phone just to name a few) but can't make a battery last longer for portable oxygen concentrator or how about contusion flow concentrator?? I have to take E tanks everywhere I need to go and since I'm on 4 to 5 Lt 1 tank last 2 hrs. I live in the middle of the country it take 1 tank to get to town and another the get home so that's 2 ! Let along I try to get as much done when I'm out. Grocery shopping, pick up prescriptions, go to the doctor's, you know all the s*** everybody has to do on a day-to-day basis just to have a life. I had to take a wagon with four bottles just so I could watch my grandson play baseball. So why can't they do better for those that have to depend on Oxygen 24/7 We are not all bed all day, we like to leave our homes, meet up with family and friends ect