I just came into 3 of these magazines, they have no markings on them other than 228 stamped on the underside of the base plate. 9mm and 40s both fit in it. The pic has 9mm loaded in it. It didn't fit my beretta 92, the only one I could find on the internet is this one for a ruger. I know there's no way of knowing for certain without seating it in one. I was hoping someone has one like it or has seen it before.
https://www.sportsmansguide.com/product/index/promag-ruger-p93-95-9-mm-32-rd-mag?a=1583599
https://www.sportsmansguide.com/product/index/promag-ruger-p93-95-9-mm-32-rd-mag?a=1583599