The rectangular welding spots are characteristic for magazines produced by Erste Nordbohmische Metallwarenfabrik (ENM). Magazines of the 1st type were only stamped with jvd on the left side of the housing and this is the secret code assigned to ENM. No other markings were applied.
The majority of this magazine variation was issued with Spreewerk (cyq) pistols. These magazines also were delivered to the Mauser factory, where they were issued with Mauser P.38 pistols produced in 1944 (byf44). The majority of the magazines issued with byf44 pistols were still in-house Mauser-made magazines.