If there's one thing I can point out in a WW1 movie from any time period, it's the fact that all of the reproduction helmets they use just don't look "right". The shape is off, and they just look bad. Well, I now have access to a reproduction that actually looks quite good, and is a very hard-to-find model for the originals.
Introduced in 1918, this version of the Stahlhelm was upgraded to no longer have the "posts" for the 1895 chinstrap, and simply attached the chinstrap via metal loops directly to the M17 steel band liner. This sped up production, and reduced superficial wounds caused by one of the "posts" coming in to contact with the ear.
These reproductions are all a size 64 shell, but will fit up to a size 59 melon. I get these, and then paint them the CORRECT WW1 "Graugrün" paint that was standard on these. This is the best and most accurate shell you can get for your impression or for display without having to spend several hundred dollars on an original.
NOTES: These are about 97% accurate to the originals (in my opinion). The only things that I can comment on that can easily be fixed/replaced if desired are the liner split-pins (originals were smaller, but it's not a huge deal) and the chinstrap. The chinstrap is not accurate and doesn't feature the aluminum clasp nor is it sewn on to the liner bails. If desired, accurate chinstraps can be had and installed, bringing this up to 99% accurate (also my opinion). You won't find a better reproduction out there.