These binding post screws are used to fasten metal or other material parts together. They are installed into an existing or predrilled hole and are fully threaded with a mating female nut component included. Measurements are made from the underside of the head to the tip of the screw to obtain fastener length. Simply thread and tighten the male screw portion into the female threaded part. The flanges on either end will bind the material between them. California residents: see Proposition 65 information