Someone gave me this cool magnifier. It’s been neat to look at things, but I’d like to know the magnification. The product’s identifying code written on the side were “Radio Shack 63–1302” which is now the code for a thermometer they sell. So I am guessing the product is older.

I looked online for similar looking magnifiers and couldn’t find anything that looked like it. I was assuming I’d find a look-alike like all 10x loupes are about the same size, so I’d find a loupe that looked like this one—but I couldn’t find one that matched.

My last resort is to find a really friendly jeweler and ask them what they think it is. But that’s relying heavily on their kindness.
So I wondered if anyone here had an idea of how to find out the magnification.