This was done in order to help identify the shell size and maker. These markings were always placed in one of two places; the center of the left underside rim or the center rear of the skirt. This alpha-numeric code contained both the maker's initials and the metric shell size of the helmet in a single line. These markings were placed on all helmets made during World War II.
The numbers denoting the maker's mark and shell size were was placed on the left side of the helmet under the flared skirt. The firm of Quist moved their maker's marks to the rear of the helmet sometime during 1942 or 1943. These marks remained in that location for the duration of the war. In addition to the factory maker code markings, a second set of stamps were placed into the shell to denote which production run (or lot number) the helmet had come from.
Virtually all wartime manufactured helmets have the production run number stamped into the shell. Only some of helmets do not and the reason for this remains unknown. Combat helmets show the markings at the rear of the helmet as do civic model helmets used by non-combat related organizations. The production run number generally took the form of three or four digits representing the production run that a given helmet came from. The production run number is sometimes referred to as a "lot number" or more specifically a serial number." Occasionally helmets were also stamped with a "DN above the production code at the back of the skirt. The "DN" was a patent mark that indicated that the helmet was manufactured in Germany. The item "Original Nice Rare Quality WW2 German Eastfield Troops M-35 Helmet w. Certificate" is in sale since Friday, February 02, 2018. This item is in the category "Collectibles\Militaria\WW II (1939-45)\Original Period Items\Germany\Hats & Helmets". The seller is "vintage-happiness-2017" and is located in Chonburi. This item can be shipped worldwide.