Castle family (Linotype library) contains 4 fonts.
This family, which includes faces in light, book, bold, and ultra weights, more stroke contrast than is typical of sans serifs, making it very legible in text.
Because of its large x-height, it is recommended for used in point sizes ranging from 12 point upward. Of course, it functions well in display sizes, too.
The contrast between the four weights makes this family optimal for use in hierarchical advertising systems, and corporate identity uses.