The grade 5 steel heavy hex nut with left-hand threads has a plain finish and meets American Society of Mechanical Engineers ASME B18.2.2 specifications. The heavy hex nut is taller and wider than a standard hex nut for a stronger hold and better security. It has six flat sides that a wrench can grip to turn from the side, enabling use when there is no space above the nut. Grade 5 steel, composed of quenched and tempered medium carbon steel, is often used in applications where strength is the primary consideration.

Nuts are internally threaded fasteners that are used with bolts and threaded rods and studs to connect components. Several different nut styles fit a variety of application and installation requirements. Some styles, such as hex nuts, acorn nuts, flange nuts, and coupling nuts, must be tightened with a tool. Others, such as eye nuts, thumb nuts, and wing nuts, can be tightened by hand. Some nuts have a self-locking mechanism, such as a nylon patch or distorted threads, that makes them suitable for applications with a high amount of vibration.