Helmets without browguard (Stirnbügel)

[Doc]

I would have to agree with Bryron about the line. Also, right above the rivet heads that hold the cheek piece, there is some sort of bulbous pertrusion that appears to have some circular shape. I would think this is where the rivet holes would have been for the peak. They are in line with the "line" that Byron mentions. Also if you follow the line mentioned all the way to the other side, you can see that there is a slight albeit very even and arc-like indentation. I would have to say that there was something there at some point that was pushed against the bowl.