Question about East German adjustable liner

[Gefilde]

Hello there, it seems like we have a lot of discussions about the M56/76 helmet, but relatively little into the liner itself; I have heard many people claim that the high-sitting liner pattern helps to reduce the damage on soldiers, especially under nuclear explosion shock wave circumstances.

We have found two major patterns of liners from the early and latter eras, the biggest difference is on their top(the crown part). Does anyone have any idea, that what purpose this part served?

[Gefilde]

In the first generation, the top part was held by little plastic nibble pins and the later versions seemed to be glued or melted with the bottom part. We can see in the last generation, that it was formed as a unibody with the bottom part. This part must be served for some reason(providing extra support or strengthening?), any idea?

[Eschborn]

yes the shock absorber disc is "riveted" then heat-sealed on the first versions. Then in 1980 appeared the new cap and the new shape of the shock absorber cast in one piece.
I only see a question of economy, simplification and ease of manufacturing for this change...