I might be wrong, but I think this maybe mystery is solved by the fact that this pipe is found in Japan. Here is a Stanwell Vario with a Regd. No. on it. First of all, I don’t see any evidence that various were made in the patent era. Second of all I’m positive that this is an acrylic stem and pretty sure it’s NOT a replacement either. Thoughts? I think the answer might be that weird things happen in Japan or, more correctly, licensing or some such requirements were different here.