RelicHunter99, it is indeed a Model 1916 German steel helmet, with, what looks like original finish, albeit worn. It is missing its M91 chinstrap mount (hole in skirt), and looks to be a small size 62/64 looking at the size of the vent lug. It will be maker marked on the inside of the skirt, forward of the "hole", for example "ET64" this will give the maker and size. They are going up in price, even just a "shell", I would say around £100+ ($150), a bit more from a dealer. Prost ! Steve.
"The German Army is the perfectly adapted, perfectly running Machine. The difference is that the Germans are organised with a view to War...with the cold, hard, practical and business-like purpose of winning victories."
G.W. Steevens - The Daily Mail (1897)