Another post war German M35/53 Helmet but this one does not have the vent holes.
This helmet has also been made by Linnemann - Schnetzer.
1909 Founding of Linnemann-Schulte & Co. GmbH in Ahlen
1948 Name changed to Linnemann-Schnetzer KG
1950 First steel compressed air tanks manufactured in Ahlen
1960 Start of serial production, introduction of custom product solutions
1992 Founding of the Linnemann Schnetzer Group, with four European production facilities
2004 Linnemann Schnetzer Group acquired by Frauenthal Holding AG from Austria
2012 Linnemann Schnetzer and Frauenthal Automotive united as one brand
I enjoy looking up all kinds of back ground information in relation to helmets, these are some links to very interesting websites:
I haven't found any information yet that showed the company Linnemann-Schulte & Co GmbH made any helmets during ww2, I found this Taschen der nachrichtentechnik Fernmeldetornister.