Self-locking Nut it is a nut that has a hexagonal shape, but its main difference is in the cut sides. The main advantage of this mount is the transmission of torque, the value of which is manifested in the interaction of the nut with a special tool.
Scope most often used in aggressive environments where the impact of strong vibrations on the structure is possible. in combination with a grover or with a washer you will get a connection which even at strong vibrations will not allow a design to disconnect.
Material Stainless Steel. The A4 steel grade allows to use fastenings at considerable differences of temperature and in the aggressive and humid environment.