Socket and set screws are used to secure one object within or against another one. Shoulder screws, also known as shoulder bolts and stripper bolts, are used frequently in pulleys, linkages, and other moving parts. They also function as guide screws or precision spacers. Socket head cap screws are used in machine assembly, or engine and machine maintenance. Headless socket set screws are also used with pulleys or similar machine parts in a shaft for a wide range of engineering, machinery, and vehicle applications.