I was going to add my article but see you already did! quite a few of those Eley ads talk about the shot concentrators and talk about the different styles and types and colors, etc. For anyone browsing, it's worth reading through. I have since picked up like 6 more of these advertising sheets since I wrote the article.

https://aaronnewcomer.com/w-c-eley-eley-bros-and-eley-brothers-limited-advertising-sheets/

I also just bought a collection of 50 or so variations of them. I'll photograph them all some day.

[Linked Image from photos.smugmug.com]