You are using the term "lens" -- normally a lens is attached to the camera body directly. Are you wanting an adapter for the thread-on filter?
What you are looking for is called a "Step up ring" -- but note they're typically "step up" and not "step down". You'll get vignetting (dark areas around the edges and corners) if you try to use filter which is smaller than your lens' filter diameter. Going larger typically isn't a problem.
So I'm not sure you'll find such a thing as a "58-55mm step down ring".
It sounds like its one of those auxilliary lens gadgets that advertise for telephoto. Basically a magnifying glass that screws on the front of a lens.
Quality generally isn't very good from them, but since you already have it, Google "58-55mm step down ring"
B&H has them; can't link to it - against forum rules.
It says 70-210 MACRO and attaches to a body with 55. I have pix if that would help.
Hmm. Does it have a make and model number? It almost sounds like an old film lens from 30 years ago, or so, which means it is most likely not worth the time and effort to try to use it.
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