This item was obtained at the estate sale of a former aerospace engineer with a long history including the development of the Apollo module rocket engines. The pin was manufactured by Boeing.
STS-133 (ISS assembly flight ULF5) was the 133rd mission in NASA’s Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discovery’s 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011. The crew consisted of six American astronauts, all of whom had been on prior spaceflights, headed by Commander Steven Lindsey. The crew joined the long-duration six person crew of Expedition 26, who were already aboard the space station. About a month before lift-off, one of the original crew members, Tim Kopra, was injured in a bicycle accident. He was replaced by Stephen Bowen.
The mission transported several items to the space station, including the Permanent Multipurpose Module Leonardo, which was left permanently docked to one of the station’s ports. The shuttle also carried the third of four ExPRESS Logistics Carriers to the ISS, as well as a humanoid robot called Robonaut. The mission marked both the 133rd flight of the Space Shuttle program and the 39th and final flight of Discovery, with the orbiter completing a cumulative total of a whole year (365 days) in space.
The mission was affected by a series of delays due to technical problems with the external tank and, to a lesser extent, the payload. The launch, initially scheduled for September 2010, was pushed back to October, then to November, then finally to February 2011.
STS-133 details courtesy of Wikipedia.