The yellowish-green Perspex box is closed off with bands of pickled steel. The works that Donald Judd set up in the exhibition space were industrially manufactured materials. He was less concerned with the artistic signature, which had to be reflected in his works, than he was with the intellectual concept - an attitude with which he differentiated himself markedly from Abstract Expressionism. From 1964 onwards the American artist created three-dimensional, free-standing objects. They were designed to make colours and forms tangible in their true presence. Depending on the incidence of light and the objects' location, the viewer's visual experience of the fluorescent surface, the reflective steel and the enclosed space varies. Visitors to the Städel will see this particular work, which is 50.8 centimetres high, on display without a pedestal. Given this manner of presentation, the contents of the box are perceived as part of its surrounding space. Judd thus makes clear that the surroundings of the artwork - the exhibition space - are a determining variable in the appreciation of art.