We were talking about wheeled bags for oxygen cylinders. The one I mentioned is called Sidekick. Hope this helps.
Wheeled oxygen carriers: We were... - Lung Conditions C...
Wheeled oxygen carriers
Hi
ebay.co.uk/itm/O2-Sidekick-...
Although lightweight I could not really find it suitable, less so with the small wheels, not very good on paved areas. Went back to the supplied trolley with bigger wheels.Air Liqude.
I actually bought this trolly bag from Amazon over two years ago and it cost then £100 and I had to pay £30 import tax when it arrived (from the US).
I find it very useful and I take it everywhere apart from into friends home because I've been pulling it outside. I also don't use it where it would be bulky such as the theatre or restaurant. I have since been given one from my oxygen provider with more pockets than the Sidekick. I no longer use any handbag when I go out because I can fit everything in the trolly bag that I would have in my handbag.
I haven't found it difficult to pull it over paved areas. I would think gravel would be extremely difficult, grass is slightly difficult for me to pull but if i'm with someone strong such as my husband he will pull or carry it for me.