This watch was
intended and destined solely for military use.
Part of the specifications was that the rotating bezel could be locked at any
given position, this to avoid any accidental mistiming.
The bezel once positioned at any required position it would lock itself making
use the protecting crown lever, which therefore had two principal functions.
The developed part was made of elastomer and it needed replacement after a speculated 100 hours of use.
Also, because this piece was destined for military use, it could not have been issued in any reflective material!
I am still searching more info, if any I might keep you informed..