7610.90.00.20—Aluminum structures (excluding prefabricated buildings of heading 9406) and parts of structures (for example, bridges and bridge-sections, towers, lattice masts, roofs, roofing frameworks, doors and windows and their frames and thresholds for doors, balustrades, pillars and columns); aluminum plates, rods, profiles, tubes and the like, prepared for use in structures, sheet-metal roofing, siding, flooring, and roof guttering and drainage equipment