Ah ok, it reminded me of some biker helmets I have seen.
Some original parts but this poor helmet has been worked over pretty badly. It looks like it has original paint up in the dome that might be Luftwaffe gray, not too clear on that though. The liner has some real problems, maybe even a larger size wedged into a smaller band. Can see that the pins holding the leather are not vintage WWII and can also see that at least one of the split rivets goes through both the inner and outer liner bands.
Not much you can do with this except strip off the post war paint and maybe do a little restoration work on the liner. The strap is not WWII German as others have mentioned. The only saving grace to this one is that it is a pretty early ET shell with the early maker mark and a fairly low batch number. It deserves a better fate than it got!