The grade 2 steel hex nut has left-hand threads and a zinc-plated finish, and meets American Society of Mechanical Engineers ASME B18.2.2 specifications. 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 2 steel, composed of either low or medium carbon steel, is often used in applications where toughness is the primary consideration. The zinc plating offers corrosion resistance and has a reflective appearance.
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.