1/4" NPT HSS DIE NUT
Taper thread, National Pipe Thread Taper (NPT), whose diameter increases or decreases along the length of the thread.
Die nuts are suitable for repairing damaged or crossed threads or clearing swarf from threads.
When using a die nut it is not necessary to apply the same level of precise initial alignment required to form a new thread (i.e. with a die) as the nut will follow the existing threads.
They are supplied as hexagon allowing them to be turned by a standard spanner or adjustable wrench without the need for a die stock.