Luger Mags

Does anyone know who made the Luger Mags with black plastic bottoms having concentric rings on the sides similer to the Navy wood bottom type? I purchased several years ago from the Collectors Armory that were in a batch that came in with the Lugers imported from Norway. The mag bodies are blued and appear well made. However no proofs or manufactuers marks were on them to determine who, when or where made.