This is a rubber black cap that protects the spacesuit glove when it is in storage or transport. It fits on the aluminum connection at the wrist of the glove. This object is part of the Space Suit Assembly Extravehicular Mobility Unit (SSA EMU), which is the spacesuit and primary life support system that astronauts wear when performing spacewalks from the American port on the International Space Station. The spacesuit is designed to be reusable and adjustable with interchangeable parts to fit a wide range of astronauts. A version of the EMU has been in use since 1983 on board the American space shuttles. Over the decades, individual components of the suit have been modified and upgraded to improve astronaut comfort, mobility and safety.
ILC Dover, the company that is the primary contractor for the SSA, transferred this item along with a large collection of other components of the spacesuit to the museum in 2013. Each item was used in testing or fabricated as part of new design efforts and bears the clear markings in red as "scrap" or lines through the label. ILC used these markings to assure that the objects would never be reused in testing or flight.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.