These vises offer a lot of value for the money. Every one I’ve seen has a very well made base and jaw whose fit, precision and finishing seem uniformly excellent. But they don’t work together as well as they could.
The problem lies in the screw and nut mechanism. I don’t know why they call them ‘screwless’ because, obviously, they have one. It just works differently and, in my experience, not very well. Conceptually, the idea of applying pressure both downward and inward is great. Functionally, though, the implementation is shoddy and causes frustrating inconvenience in use. It really does need some work.
Not to worry. The fix is easy for a machining hobbyist and the vise can be made a pleasure to use. This paper decribes how I modified mine.