I bought my wife the portable oxygen concentrator , to make life easier and less embarrassing when going out having to carry oxygen bottles around all the time , with the in car charger it makes life easy traveling around and mains charger means you can plug it in when you go out over night any were , I know it was a expensive price but you can’t put a price on see here more mobile and getting out more to see our kids that live 2 hours away , she has got her life back would recommend that don’t think abought the price just buy it and see there life’s change for the better