The rectangular welding spots are characteristic for magazines produced by Erste Nordbohmische Metallwarenfabrik (ENM). JVD is the only marking found on the left side of the housing and this is the secret code assigned to ENM.
If you look very carefully you can find a stamp on the bottom of the spine. This stamp is the Spreewerk acceptance stamp E/88 and indicates that the magazine is approved by the Spreewerk factory. Unfortunately the stamp on this example is difficult to see.
ENM Magazines of the 2nd type are comparable to magazines of the 1st type. In addition to the 1st type, these magazines have the Spreewerk inspection stamp (E/88) on the spine. These magazines were issued only with Spreewerk pistols (cyq).