Issued by Netherlands (Nederland), this striking semi-postal set features bold modern geometric cube and hexagon designs rendered in vibrant contrasting colors. The minimalist optical-style artwork reflects the strong Dutch graphic design movement of the late 20th century. Each stamp carries a surtax (indicated by “+” values), supporting charitable causes—an important feature for thematic and social history collectors. The clean typography and three-dimensional cube illusion make this set highly desirable for collectors of modern art, geometry, design, and semi-postal issues. Well-centered examples with fresh colors are especially attractive for display in thematic exhibits.