I’ve been offered this Imperial Prussian M15 Pickelhaube which is in a nice used condition (albeit for a missing liner tongue). I have a question regarding the rear visor which appears to have been re-attached at some point as a row of holes is visible above where it is stitched to the body of the helmet. Overall, the wear to the haube and rear neck guard appear to be commensurate with one another so I am wondering if it may be a depot replacement/repair or similar? I don’t see an issue stamp but assume it it there but hard to see due to the darkened leather.

Thanks for any advice regarding the rear neck guard.
Andy