This device is excellent! Here is my review.
Per a couple of direct and indirect comments. I have no specific reason to believe that narrow piece of rubber across the thumb will break, I was just saying that was a consideration - and it peaked my interest. I have a snorkeling mask I have used 100s of times with that rubber piece that holds it onto my head and it has worked flawlessly with no tears or wear and rough treatment, so high quality rubber is impressive. I expect if you take this off gently it will last a long time, especially if you dont take it into the ocean :).
Note - I have no association with the Wellue company that produces this. I am just somebody with multiple things that can limit my nightly oxygen intake and I am testing non medical grade devices to see what helps.
