Akust External Clinch Screw are steel machine screw that have a free spinning washer on the shaft. Akust External Clinch Screw was designed to have the teeth from the washer attach to the base of the material so the screw cannot come loose caused by vibrations. Akust External Clinch Screw are designed with the purpose to prevent any loosening of the screw and to prevent corrosion on the head of the screw.