what kind of meat is used at carving stations?

If I go into a cafeteria and they have a hunk of meat on a carving board that the cafeteria is calling "roast beef"; generally what cut of meat is used? The cafeteria slices it very thin about an eighth or an inch. the serving size is 1 to 3 slices.

I know it is not Prime rib. it is cut too thin to be Prime rib.