The steel machine screw has a zinc plated finish and a flat head with a slotted drive, and meets American Society of Mechanical Engineers ASME B18.6.3 specifications. Steel is often used in applications where strength is the primary consideration. The zinc plating offers corrosion resistance and a reflective appearance. The slotted drive has a linear slot for use with a flat-blade driver. The flat head is cone shaped for use in countersunk holes and has a flat top that fits flush with the mated surface.
Machine screws are threaded fasteners that are typically used with nuts or drilled and tapped (threaded) holes. Machine screws are available with a variety of head shapes, which determine how the screw interacts with the mating surface, and drive styles, which determine the type of driver required to install and remove the screw.