19 Building materials and elements, not of metal; building panels, not of metal; roofing, not of metal; non-metallic roofing elements and building materials for roofs; multi-layered insulating glass units for glazing buildings; glazing materials and components; plastic building elements and panels; windows, window frames, doors, door frames, translucent building elements and panels of plastics and roofs made therefrom, translucent roofing materials; panels for structural purposes; structural panels for use in the construction of buildings, walls, and floors; structural panels; structural building panels; parts and fittings for all the aforesaid goods.