The HumidiFlyer Junior mask is the standard mask with a removable insert inside the mask.

You can clearly see the insert in the image

This effectively reduces the size of the opening in the mask to be able to fit smaller faces.  Many women are using this mask as they can generally have smaller features.  The mask is useful for children 6 years and older.

Girl friends in the airplane

As the child gets older they will get to an age where the insert can be removed.