MS21042-L08 ALL METAL STOP NUT 8-32

All metal stop nut for high
temperature installations to 450 degrees F. MS21042 non-corrosive
self locking nuts are fabricated from carbon steel per specification
QQ-P-416C. 160,000 PSI Tensile Strength.  Sometimes called "Kay" or "Jet" nuts. They have a
ring base for positive seating, a reduced hex for better wrench access.