Description of Union Butterfield Round Threading Stocks
Die Stocks. Designed for use with adjustable round split dies. The die is held securely by two opposed screws in the stock which locate in two indents in the die.
These threading dies may be suitable for small projects at home, but they are not suitable for industrial and scientific applications. The quality is subpar and the threading is inconsistent, leading to a frustrating and time-consuming experience. .
Description and manufacturer part number are incorrect. But the picture is correct. I don't know what it is, but it's not a D3 stamp. This is a piece of a shaft and a bushing of some sort.