Calder hung abstract shapes from rods. The balance point was where the rod was hung or supported. His mobiles were always asymmetrical but they were balanced in weight or else they would tip on end. He made this large sculpture in 1973 for a square in Stuttgart, Germany. It is called Crinkly with Red Disk. One circle balances two irregular polygons that are on another rod. The balance depends on the weight of each of the parts and where the balance point is put.