The external diagrid is composed of hollow square sections 600 x 600 millimeters on a side. They carry floors four meters high. Each diagrid member is a different length, depending on the angle at which it leans. The external diagrid elements are made from welded steel plates, 80 millimeters thick at the bottom floors, and progressively lightening to 40 millimeters at the top floors. The internal diagrid around the atrium is made of round steel profiles 400 millimeters in diameter, which are also hollow.