I use them on 100 lb-ft plus nuts and they are holding up very well. I also use them as regular sockets where they fit. The inside is shaped to avoid rounding the corners of the nut, and put pressure on the flat part of the nut. A good idea.
It's made in Taiwan and not made in the USA as shown when I bought it online
sent me the deep set when its clearly the shallow set. complete waste of time