The steel machine screw has a zinc plated finish and a flat head with a Phillips drive, and meets Deutsches Institut für Normung DIN 965 specifications. Steel is often used in applications where strength is the primary consideration. The zinc plating offers corrosion resistance and a reflective appearance. The Phillips drive has an x-shaped slot that accepts a Phillips driver and is designed to allow the driver to slip out of the head to help prevent over-tightening and damage to the thread or fastener. 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.