Aiwa TM Plastic Socket Wrench Set (Grey, 10-Pieces) Spark plug socket ratchet handle set. A socket wrench is a type of wrench or spanner that has a socket attached at one end, usually used to turn a fastener. The most prevalent form is the ratcheting socket wrench, often informally called a ratchet. A ratcheting socket wrench is the device within a hand tool in which a metal handle is attached to a ratcheting mechanism, which attaches to a socket. This in turn fits onto a type of bolt or nut. Pulled or pushed in one direction, the ratchet loosens or tightens the bolt or nut attached to the socket. Turned the other direction, the ratchet does not turn the socket but allows the ratchet handle to be re-positioned for another turn while staying attached to the bolt or nut. This ratcheting action allows the fastener to be rapidly tightened or loosened in small increments without disconnecting the tool from the fastener. A switch is built into the ratchet head that allows the user to apply the ratcheting action in either direction, as needed, to tighten or loosen a fastener. Other common methods of driving socket wrenches include pneumatic impact wrenches, hydraulic torque wrenches, torque multipliers and breaker bars. Some lesser known hybrid drivers include striking wrench tools with square drive, and hydraulic impact wrenches (typically powered by on site hydraulic power such as present with military tanks, and many rail car applications).