Alexb2000
En-Route
I take it you like this O2 monitor?
Looks to me like one plant in China is pushing out a bunch that look identical, but are sold under different labels with different prices. I see the exact same model as I linked sold for $90 under in home medical area. I have a couple of different ones and cross check them once in awhile and they all seem to agree. So that said, yeah, it seems to work fine.
I also like to use them to tune the flow of O2. Different people have different needs so just following the altitude marks on the canualla/mask doesn't always cut it.