I might consider extending the  under jaw of the mask so that it as fit the width of a double D seal as well, however the fitment seems good right now, so we will not make any changes. Even opening your mouth completely like your surprised still pressed against your skin. One way to offer personal adjustment is to offer different thicknesses in D seal so that the user can try it out and make adjustments when needed. The double sided tape holds the seal secure but whenever it wears out, it can be peeled away and replaced at any time. 

Please take the time to give this project a like, I would really like it to become a real product I can get into the hands of people who need it as soon as possible. Thank You!

Please take the time to give this project a like, I would really like it to become a real product I can get into the hands of people who need it as soon as possible. Thank You!

9mm thick on each side of the nose does a good job of creating a comfortable seal

Please take the time to give this project a like, I would really like it to become a real product I can get into the hands of people who need it as soon as possible. Thank You!