Exhibited outdoors in Toronto in 1967 and at Dan Flavin’s retrospective in New York in 1970, the enamel surface of this work sustained damage; subsequently, Donald Judd used this object to test methods of repair, which resulted in the varied surfaces of the individual units. “Four units in a row are only that,” Judd wrote in 1993. “They are not part of infinity, either endless or above or within. They are a small, finite order that I am interested in.”1