Is your mushroom posy optic ribbed, Keith?
I do have a habit of suspecting S&W for threaded pieces, but I don't know how many other makers used it too.
I don't feel the little glass in question could be Keith Murray, because I like it. It's curved and elegant. I normally have a very strong aversion to anything KM designed, it's generally full of straight lines and angles. (We can't all like the same things.

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