TRASER 3105 S, 2005
Here are the parts...
That tight fit of the bezel with the case is achieved by that inner metal ring. The white ring contains four little tongues that provide the ratcheting. The four legs of the white plastic "click spring" fit into the four holes in the case at 1:30, 4:30, 7:30 and 10:30.
It is only an optical illusion (crystal acting as magnifying lens) that makes one believe that the inner bezel containing the Tritium bezel seems to be connected to the crystal. While I have not removed the case back yet, I am sure that after removing the stem, the spacer and then the movement, the inner bezel ring with the vials is simply resting on the case underneath the crystal. Thus replacing the crystal is standard procedure.