H.S.S. 2-80 dies are very rare. They are designed to thread 2-80 micro precision threads on rod stock. These threads are used by knife and gun makers to create a maximum adjust threading, or to create a thread that is less prone to "back-out", a common issue with standard coarse threads.
Try a 2-80 thread on your next project and you'll never go back, or back-out again!!!
Die Thread - 2-80
Diameter - .80
Fits 13/16ths die handle