Wow what a nice KM helmet!!
Here is a beautiful example of one of the 1940 contract SE KMs whereby SE (Sachsische Emaillier u. Stanzwerke in the city of Lauter, Germany) must have gotten a large contract for KM helmets right around the time that they were changing the appearance in the first half of 1940 and so still had a lot of recently minted M35 shells lying around with which to fulfill their KM order. Most of these SE KM M35s factory finished to M40 specs (feld grau textured finish) are found in the 4000 lot number range as is this one with a lot number of 4860.
Unlike a lot of dark tea toned Heer SD helmets there is no mistaking this one as a true Kriegsmarine based on the decal's "golden" metallic luster and most importantly it's 3-D layered design which can be seen as a raised edge line at the top and bottom of the wings and around the bottom of the swastika. The raised golden eagle on the black shield background is a characteristic unique to KM helmets. The inside liner is re-enforced aluminum outer banded with rounded bale chinstrap loops which are mainly seen in the first half of 1940 just before factories began switching over to steel banded liners.
The doppelganger of this exact type of SE KM M35 helmet appears on Ken Niewiarowicz's book on page 98 lot number 4864 with a similar condition decal making this helmet a true textbook example.