6" diameter of the top. No markings that I can find and an unusual bearing arrangement. At first I thought the top was custom made, and now I'm wondering if the whole thing could be. Every vise I own has some sort of markings somewhere except this one.
really an unusual find. never seen one like that. the bottom looks like muelmat. perhaps a machinist, long ago, made a top for it.:biggrin: a great gift from jj.