Question regarding USMC cover

[ackb]

I have a few USMC helmets in my collection and saw recently this piece for sale as a original non issued ww2 example.

I have some concerns about it and wanted to ask you guys. Pictures are very poor but it looks like the thread along the edge is some kind of silver.?

I have only seen such covers with the light brown collared thread as on one of my own shown in the last picture. Can one of you confirm that this type of thread is the only one used or is it normal to see other types?


Cheers
Alex