LSAT wrote:...it's for high altitude use.
lol No, it is not for high altitude use. I live at 35 feet above sea level and the gym is two blocks away. There is a young guy who wears one of these every time he works out at our gym. I asked him about it one day and he has it set at 15,000 feet when he works out. He mainly wears it because it makes your heart and lungs work harder and he thinks he gets a better workout. But he said a side benefit is he is better able to handle the altitude when he visits the Rockies every summer for hiking with a backpack.
I told him I like the idea, but I would not be wearing one because I already wear a CPAP mask seven hours a day and that is enough mask for me. I expected he would ask what is a CPAP mask and I was surprised when he quickly said his father wears a CPAP mask.
Huh?, I would suggest you also may want to take a rest from masks during the day. Are you planning high altitude hiking or running?