That looks just like a set I bought at HF for $9.99.
Mine is made in China and I later found out that they are chaser dies, not cutting dies. They are meant to clean threads before assembly.
That was the information I was given after I couldn't get them to cut any threads and had to ask.
They don't do a very good job of cleaning threads either. They aren't the same threads as the bolts or nuts.
I hope yours are better and work for what your intentions for them are.