Hillman Round Head Machine Screw, 10-24 x 2 In. Machine screws are designed to fasten metal parts together by either being used with nuts or screwed directly into a threaded receptacle. The length of the screw is measured from the underside of the head to the tip, ensuring an accurate fit for your fastening needs. For optimal performance, it is to use nuts that match the finish and threading of the screws. Model Number: