Having six edges, or having a cross-section in the form of a hexagon. Hex Head may refer to screws, bolts, or wrenches such as Allen keys, Allen screws, or Allen wrenches. In restaurant equipment design, sockets are common engineering elements. In general, sockets are receptacles for matching parts, tools, and components. They may serve only for mounting purposes, or they may be used to form connections and provide a source of power.