Several years ago, I picked up the M40/42 on the left. It originally had a built-in microphone, as seen below. I know those rings are related to the mask, but I forgot if either of them was supposed to have been installed with the voice diaphragm or if they were simply spare pieces that came with the extra voice diaphragm I picked up (any info on whether they should be installed or not is appreciated).
To the right is a newer M40 I picked up with the intention of getting a large in practically brand-new condition. However, it has a deformed oral nasal cup. Interestingly, the silicone between the two has noticeable differences, with the left being able to grip the face and seal much better, but being tougher, while the right is softer but does not seal as well (both are mediums).
I am interested in retightening and setting the first mask back to its original voice diaphragm. If anyone knows where I could pick up the tool to remove/tighten the voice diaphragm screw, that would be appreciated.