A doubt about my Kugelhelm 10° FAR

I have a question because I'm unsure (forgive me , for sure is a silly/beginner question)....
Let's talk about the Kugelhelm 10 FAR I posted.
I described the helmet as a model 91 because (I thought) the "hinterscheine" doesn't have vent with sliding cover...
but it's probably is a model 95, and since it's a mounted troops helm, it doesn't have the aforementioned vent.....
I'm sure, with your knowledge and experience, you'll be able to clarify my doubt.
Thanks for the help
Giorgio

Hello Giorgio,
that's exactly right.
Until 1895, the rear spine of all spiked helmets, without exception, had no upper ventilation flap and no vent under the neck guard. This refers to the M71 model.

In 1895, helmets for infantry troops received these vents (infantry, foot artillery (heavy, siege, position, and fortress), and pioneers). The only exception was the Train Battalion, which also had these vents.
***Other spiked helmets (Dragoons, Field Artillery, etc.) retained the older 1871 spine design.

Above, two identical helmets from the same regiment. On the left, M71 and on the right, M95 (because it was an infantry regiment).
Regarding the rear ventilation, M95, this does not apply to infantry officer helmets or Eigentum helmets for one-year recruits (not regulation in this case).

M71 for all Fastening by "button-rivet" with folding tabs. :


M95 F.A.R. and Dragon :Same as M71 but screw-nut fixings under the neck cover. .



M95 Infantery ( trupp).

Wow...as always, you're truly invaluable, Thierry....
So I have an "M95 mounted troops (Artillery)"...
But forgive me if I'm taking this opprtunity...I don't quite understand the "ventilation" of the hinterscheine at the base of the rear brim (as pictured). When do we find it? Or rather, on which helmets exactly we can find it?
Thanks again
Giorgio

Tous les casques dotés d'une dorsale arrière mais dépourvus de volet de ventilation n'ont pas d'aération sous la nuque. (Casques d'infanterie M60, Dragon, M71, etc.)





---However, from M95 onwards, the spiked infantry helmets (JR, PB, AzuF, TB...) have a flap behind the spike AND a vent on the return of the rear spine under the neck guard.



In fact, to ventilate, you need an inlet and an outlet for air circulation.

Sorry for the late Thierry......really thanks for the explanations,,,
Giorgio