Magazines of the 12th type are marked with the ENM code jvd on the left side of the housing. The position of these markings can vary. No markings were applied on the spine. The right side of the magazine housing is stamped with the model designation P38 above a large U. The letter U was stamped under the P.38 marking to indicate that the magazine lips were not hardened. It is believed that the U is an abbreviation for the German word ungehärtet, which translates to unhardened. The hardening process was not longer necessary because of a design change in the magazine follower. The new grooved follower used for these magazines increased the stability of the magazine in such a way that surface hardening became unnecessary.
These magazines were issued only with Spreewerk pistols from the Zero and Double Zero Series Spreewerk pistols.