Thanks Francis.
To do a little comparing; :study:
The spike on the Holdefleiss is made out of two pieces, and not often seen in this way, maybe here ,still in a state of development.
The wappen on the Lachmann and the Weissenburger are identical, the inside lugs are square.
The wappen on the Holdefleiss has the pointy banner.
The liner in the Holdefleiss is black and in the others with untreated lamb skin.
The cockades are all of different sizes ,the smallest is on the Lachmann ,just like the infantry helmet ,slightly bigger is the one on the Weissenburger ,and the biggest is on the Holdefleiss.
The neck tail of the Lachmann has an extra weld finish, while the others don’t.
These are not rules ! just observations ,it would be perfectly possible, during the years of production ,that for instance Holdefleiss suddenly decided to make helmets with untreated lamb skin too .