Olivier Marin OtherSint-Gillis-Waas4/522-6-2017My oxygen saturation was still 91 percent at 4000m and felt great during our mountain bike tour at altitude. So I am very satisfied. Of course you never know what the effect of the height tent is because you cannot compare, the same situation with or without preparation. But I think it helped me anyway. My partner who is normally physically stronger than I was more bothered by the height in the beginning ... and couldn't keep up with me ???? Thanks for the good service. Greetings, Olivier