It’s a Chinese made clone of the original USA Made and designed Sawyer Nutyp vise.
There are now numerous copies of the design, that vary in quality, with almost all the copies being made in China.
The Older Chinese made copies seem to have been faithful copies of the original Sawyer Nutyp design, and seem to be well liked, or at least decently liked by those who have them.
The iron casting are sometimes not found to be perfect when stripped of paint, and routinely have Bondo or similar to smooth the castings, but the original design was made to be made from regular cast iron, so the strength is usually fine for the design.
The better modern versions are the Yost 750DI, and a similar vise from Capri, both of which are Ductile Iron, which would be stronger, and more break resistant, however, a few areas have been simplified on both, and both run $200+ new.
There are regular cast grey iron versions that are cheaper, but certain other areas have usually been cheapened as well, such as cast in place vise jaws, and lighter weight castings.
$50 seems like a fair price for one of the older, “proper”, Chinese versions.