General Information: The Helm mit Ohrenausschnitten or “ear cutout helmet” was a variation of the German Model 1918. It is identical to the standard M18 but for the half-moon curved sections adjacent to the location of the wearer’s ears. The purpose of the cutouts was to improve hearing, not as was commonly believed, to accommodate headphones for telegraph and radio operators. Nor were these helmets intended as specialty headgear for cavalry troops.
A War Ministry communication of August 1, 1918 proposed the use of the Helm mit Ohrenausschnitten and ordered 100,000. According to the specification, the helmets were to be size 64 and were to be painted with matte felt-like finish using wool dust (wollstaub). At the time of this order, test helmets had already been produced and were ready to distribute. The order mandated the distribution of two thousand one hundred of these test helmets to each of various specified units. The War Ministry provided these units with a questionnaire regarding features of the helmets. The completed questionnaires were supposed to be returned by December 1, 1918. As it turned out, events of November 11, 1918 precluded the completion of this research.
It is not known whether the order for 100,000 of these helmets was actually completed.  There are very few period photos of soldiers wearing the ear cutout helmets which suggest distribution was limited. All of these helmets were made by the Eisenhuttenwerke firm and were size 64. All therefore are stamped “ET 64” on the interior skirt section on the wearer’s left. There are lot numbers stamped on the top of the interior portion of the helmet dome. Collaborative research by collectors has put the known range of lot numbers as follows:
R 1787 N to R 1885 N
BD 567 R to BD 576 R
In the R-N series, the “N” is occasionally absent.
The great majority of the M18 ear cutout helmets (sometimes referred to by collectors as “M18 ECO”) were reissued during the Reichswehr or Third Reich period. Among the relatively small number of M18 ECO helmets that survived in their original First World War configuration, most were issued with standard paint rather than with wollstaub.
Displayed Example: I acquired this helmet from an auction house in Ireland. It is a very rare example of a Helm mit Ohrenausschnitten in factory-original condition. The wollstaub finish puts this piece in the “very, very rare” category. The lot number is R 1845 N which is the middle of the known R-N series.
Originally the woostaub finished helmets were painted something like field grey but over time they tend to take on a brownish patina due to oxidization like this specimen. I presume this is because the wool in the paint absorbed moisture. The tab on the chinstrap is nicely named to the manufacturer, “ARMINIUSWERKE, WILHELMVICK, ROSTOCK, 1918.” The short end of the chinstrap is broken in two places and held together by a clip for display purposes. As with all original ECO helmets, it is marked “ET64.” The size is additionally indicated in black ink on the back of the interior section of the helmet skirt. In the same area there is an “AK” black ink stamp where the right leg of the “A” coincides with the back side of the “K.” This was the stamp for “Abnahmekommando” or “Acceptance Command” which was the military authority responsible for inspecting procurements.
Collector Notes: The ear cutout helmet is a relatively rare member of the stahlhelm family. They are highly prized by collectors and are expensive. An ear cutout helmet in its original First World War configuration is much harder to find than transitional versions of this type used mostly in the 1930s.
The good news for collectors is that the ECO helmets have not been easy to fake and reproductions are usually easy to spot. If you compare the curved section of an original to a reproduction, the difference tends to be apparent. It has been hard for the reproducers and fakers to get the shape exactly right. The cutout part on the repros is typically too large or too wide. Helmets without an ET64 stamp are not original.
* Attribution pending
 Baer. 2001. pp56-57.
 Baer. 2001. pp56-57.
 Lock. 2020.
 Haselgrove, Michael. German Helmet Walhalla. “Post your M18 ECO helmets Here.” Post #11. 9/23/2018. https://www.ghw2.com/topic/59917-post-your-m18-eco-helmets-here/. Accessed 4/7/2022.