8x10 sets are sets of photos that were printed on heavy card stock to be displayed in the lobbies of theatres.  These sets were issued for films until the late 80's in the United States, after which some were issued for International film releases. Each card measures 8"x10" and were typically issued as sets of eight (exceptions to this are noted in the specific entry).  8x10 sets generally, but not always, depict the same scenes from the film as do the lobby card (11x14) sets issued for a specific film.  Most listings show only four of the cards in the set.