Spacewalking astronaut Bruce McCandless inspired the design of this tool handle, as denoted by the "McTether" name engraved on the shaft. It is milled out to reduce mass, shaped for handling with a spacesuit-gloved hand, and anchored by a tether ring. Tools are always clipped to an astronaut’s wrist tether or workstation to keep them handy without floating away. A socket or ratchet head could be attached to the oval end of the tool, and the long shaft served as a lever for torque to tighten or loosen bolts, especially those that could not be reached easily by hand.
This tool is probably a prototype for the tool that eventually became part of the standard extravehicular activity (EVA) tool kit on Space Shuttle missions. NASA transferred this tool to the Museum after the Shuttle program ended in 2012.