Dreamwear Mask Question - Air Holes

[DreamMan]

Their are two (2) air holes in the Dreamwear Nasel Mask.  One on top were the house attaches and one at the mouth piece.

What are these for?

This is the first mask that I have owned that has two?  Why two?  Redundency?

Reason I ask is that when my head slips down on the pillow at night, sometimes the top air hole gets blocked.  Is this a problem? or does it only need one hole working?

[Crimson Nape]

Your mask is designed with an intentional leak for CO₂ removal.   Your OSCAR Leak Rate graph will display no major change if the other vent holes are picking up the work when the top ones are closed off.  If there is a problem, your intended leak values should display a definitive drop.

- Red