The mark shown is one of the many different versions used between 1920 and 1938 - even the old Pirkenhammer site does not list them all, so '1920-1938' is the closest one comes as for a production period. Note: the Pirkenhammer site completely disregards the fact that the union of manufacturers from its founding onwards until June 30th 1920 was named OEPIAG and only on July 1st 1920 became EPIAG, hence their dating of '1918-xxxx' for EPIAG marks is nonsense. They know that and always wanted to change it, but that information (as well as the marks table) never made it onto the new website.