Some friends and I use it all the time when flying at elevation and for training breath holds for free diving. Was useful for the couple of times I had covid t

Some friends and I use it all the time when flying at elevation and for training breath holds for free diving. Was useful for the couple of times I had covid too. Which is to say it’s very useful to me a few times a month. I wouldn’t go out of my way to buy a Massimo watch for the feature though.