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.