
This is how I measured the frames. The tape measure runs from the outside of the O on the very top of the mask to the outside end of the silicone tube (where the nasal cushion would attach). As you can see, the frame curves toward the front, so the measurements are the best I could do when laying the tube flat:

S 8.5”
M 9.25”
L 10”
So there's about 3/4" difference between each one. Not sure how helpful that info will be to anyone; just figured I'd put it out there.
Happy sleeping.

