Machine screws have a uniform diameter along their entire length and are designed to screw into threaded holes or to be used in combination with machine screw hex nuts. Other nuts can be used other than just hex head nuts, washers can also make your assembly easier as well. Make sure the inside diameter matches the screw size. Typically they are most often used in machinery and appliances, however they can have a multitude of different uses. The first dimension is the size of the threaded shaft of the screw and the second dimension is the length of the screw. Each package contains 10 screws.