I'm watching your answers, and am grateful for the advice/information. Sadly, nobody can find the item the machine provider is teasing me with so far. I have looked on Lazada history to try to find a little more information on the machine, but despite showing me a picture of the unit, the description is something I ordered a couple of weeks ago, so useless. The machine itself was the last one left in Thailand at the time, and everything is in Chinese
It even talks in Chinese. I did find a manual in English when we received it to work out what the Chinese controls meant, but even that doesn't give many clues.
What does it filter out? Little more than dirt particles from what I can see. A dirty filter has little black spots on it.
I will wait a day or two in the hope the supplier comes through with just a little bit more information to enable me to order the pucker item (probably at an inflated price). Because of the importance of oxygen to my wife, I don't want to take any unnecessary risks. However, at this point in time, it is looking as if I may have little choice.