Mary,
I read your question a while ago and went to the Singer home page. Looked it up and down and did not find the Model 15s. I am also curious as I'd like to leave some finger prints on one ....
From the pictures I've seen, they look just like the 15s of old with the Sphinx decals, except they are really very shiny.
I have a case from one I bought from my LSMG. He was noncommittal and said he might still have the machine around the shop somewhere. Sounds kind of silly to me, but that's what he said.
Joe