A socket head cap screw is a type of fastener that has a cylindrical head with a hexagonal socket. It can be tightened or loosened with a hex wrench or a socket driver. Socket head cap screws are made of various materials and have different surface treatments, depending on the application. They are commonly used in places where there is limited space or clearance, as they do not require external tools to fit into the head. Socket head cap screws offer high tensile strength and fatigue resistance, making them suitable for demanding applications such as power plants, hydraulic systems, and plastic injection molds.

A socket set screw is a type of screw that has no head and is fully threaded. It has an internal hexagonal or Allen drive that allows it to be tightened or loosened with a hex key or Allen wrench.Socket set screws are used to secure an object within or against another object by creating friction between the point of the screw and the contact surface. For example, a socket set screw can be used to lock a pulley or a gear on a shaft. There are different types of socket set screws with different point styles, such as cup, flat, cone, oval, dog, and knurled.

A hexagonal wrench, also known as an Allen wrench or hex key, is a hand tool used to drive screws or bolts with a hexagonal socket drive. It consists of a metal rod or L-shaped piece with a hexagonal-shaped tip at one or both ends. Hexagonal wrenches are designed with a six-sided (hexagonal) tip, which matches the shape of the socket drive on screws or bolts. This shape allows the wrench to engage securely with the fastener, providing a reliable grip for tightening or loosening.  Hexagonal wrenches are commonly used in various applications, including furniture assembly, bicycle maintenance, automotive repairs, electronics, machinery, and other tasks that involve hexagonal socket fasteners. They are especially useful for fasteners in tight spaces or recessed areas where other tools may not fit.