It is plated to the inside of the thread mountain and it is the product as expected. There is no trouble with combination with the same dumb dipping bolt.
Purchased with a set of bolts of the same series. I was anxious about fitting because it was my first dub, but it roamed by hand with almost no problem. There was something that could not be used because one out of 12 nuts was rugged. It does not enter bolts nor spanner. Is it a defective item or a dub is such a thing?