Socket Cap Screws are reliable and durable and are used in many applications. They are available in a variety of head styles and materials. Alloy Steel is steel that has been alloyed with other materials to improve overall physical properties. Steels are designated by a 4 number SAE Steel grade. The first two digits indicate the primary materials used to form the steel. The last 2 digits identify the percentage of carbon for the alloy (in hundredths). Tensile strength ranges for the alloys typically used in these fasteners range from 170,000 to 180,000 psi (pounds per square inch), making these amongst the strongest of materials. With a high cylindrical head, socket cap head fasteners have a recessed driving area and offer high hold power at high torque levels. Hex socket drive systems are driven by hex wrenches or power tools with hexagonal bits.