In total, the R2 model covers Star Wars: A New Hope, The Empire Strikes Back, The Return of the Jedi, The Phantom Menace, and Attack of the Clones, so this isn’t simply a piece of movie history.
What makes this particular R2-D2 unique is that the item is both an actual movie prop, and something that was never technically seen on screen.
At this point you have to wonder if there’s a piece of R2 from Star Wars: Revenge of the Sith out there someplace that one could buy just to make the model complete and cover both trilogies.
According to Entertainment Weekly, the complete R2-D2 that went in a Southern California auction was made up of numerous different pieces that were all used in different films.