Non-metallic wall panels; plastic panels for use in building; cladding panels for walls, not of metal; dividing wall panels, not of metal; indoor partitions, not of metal, other than furniture for building; structural support members formed of plastic; fire-resistant panels, not of metal, for use in construction; concrete blocks; concrete block ballast; concrete blocks for supporting hoarding and partition walls; parts and fittings for all the aforesaid goods all made wholly or principally of...