Socket head cap screws are commonly used in machine assembly with limited space., also for removable panels and parts. critical vehicle applications, machine tools, tools and dies, earth moving and mining machinery, a wide range of engineering applications. They have a round cap with a hex socket head and are tightened with a socket wrench drive features (mostly hexagon socket) that allow them to be used in locations where externally wrenched fasteners aren't desirable. Choose the right cap head for your specific application. Longer caps are easier to see when fastened, while button and flat head caps are less apt to snag clothing or linkages. Chrome cap screws have a great appearance. Those with a black oxide or armor coat finish resist corrosion.The most important reasons for the increasing use of socket head cap screws in industry are safety, reliability and economy.