"Can you provide a product # for this specific item?I have been eyeballing these items for over 6 months but this is the first time this lightweight adapter has appeared."
Here's the original (ended) eBay auction that I bought mine from, they're the same details as the shop stocked item. The image enlarge and zoom features still work.
The shop in the previous link also stocked them at the time.
These are well crafted devices, the ultralight (my designation!) comprises five separate components, including a very well fabricated brass jet, and arrives in a heat sealed bag, itself in a clear storage box.
I guess that they're made in small batch production runs and when sold, the process is repeated.
I didn't really want to put an eBay contact link up at the moment, due to the unprecedented circumstances affecting those in Fukushima.