This is description of this part:
Click-stop latch spring of the objective change mechanism in the Zeiss Stemi DRC stereo microscope.
This is the part responsible for the fact that when moving (changing) the objective, a "click" can be heard and felt, and the objective stops in the correct position. This part is a spring tab that falls into a corresponding recess (latch).
Detailed photos of this element along with dimensions are available in the image gallery. Additionally, in the last image an arrow indicates which element it is and where it is located, allowing clear identification of this part.
What is this part needed for?