The HLN Hardlock Nut has a structure that prevents looseness through the traditional Japanese principle of the wedge. To effectively utilize the wedge structure, two nuts are used: (1) a convex nut with an eccentrically formed boss, and (2) a perfectly circular concave nut. When these nuts are fastened together, the wedge principle mechanically creates a powerful locking effect transverse to the bolt shaft. This powerful anti-loosening effect achieved with the HLN Hardlock Nut wedge completely fuses the bolt and nut. Once locked with this powerful force, the HLN Hardlock Nut is not susceptible to impulsive forces or shocks.