I started with it but since I am a side sleeper I would have to reajust my head and the mask constantly because of leaks.
So on Saturday night, I used the large mask to see if it would be better.
It was not as comfortable because it goes lower near my upper lip.
But in the morning I had NO AHI! I went back on the s/m afterwards not being sure if I should be using the other.
This week at my appointment at the clinic he said my data was good with both masks so its up to me.
Is there a medium one somewhere I can buy??? They have s/m, L and XL in the bag.