Found this among my dad's stuff. It's a .32ACP mag, he didn't have a .32ACP gun when he died. But over the years I know he had the following .32s: Dreyse 1907, CZ 27, CZ 50, CZ 70 - I suspect this is for a CZ70, which I think was the last .32 he had. Whatever this is for - it's a heel release gun.
I'm hoping the PF Hive can help me ID this, so I know what gun to buy to fit it.