A machine screw is a fastening screw with a machine-cut thread throughout the length of its shank, for use with a nut or driven into a tapped hole. Use to fasten various components together in machines, tools, etc. The length of a machine screw is measured from under the head to the point of the screw. The truss head has a low rounded top surface with a flat bearing surface, greater in area than a round head fastener of the same nominal size. They are weaker than a pan or round fastener, but preferred in applications where minimal clearance exists above the head. The profile provides a trim, finished appearance.