Hex nut with an enlarged circular base ﬂaring out from the bottom of the nut. The bearing surface of the ﬂange has serrations which displace material on the mating surface when the nut is wrenched into place, forming a connection which resists loosening.
Requires a greater amount of torque to loosen than to tighten the nut. Will span oversized or poorly aligned holes. Flange provides a more uniform bearing-stress to clamp-force ratio than other low carbon lock nuts. Does not gall screw threads.