This is an apolitical forum for discussions on the Axis nations and related topics hosted by Marcus Wendel's Axis History Factbook in cooperation with Christian Ankerstjerne’s Panzerworld and Christoph Awender's WW2 day by day.
Founded in 1999.
Its the manufacturers marking and size along with the lot number. Its supposed to read CkL 66, CKL (ET) made helmets this late in the war had missed and lightly struck stampings, this one is missing the L. Also, the lot number 5X73, has a lightly stamped second number which is unreadable. This is a late war M42.