19 Non-metallic construction materials; non-metallic rigid pipes for building; plastic boundary marker stakes; panels not of metal; panels, not of metal, for building; fence panels, not of metal; door, entrance gate and fencing panels, not of metal; signage panels not of metal; hardboard; multilayer panels of plastic materials for building; non-metallic perforated panels; sheet piles, not of metal; floor boards of plastic materials; masts (poles), not of metal; fence posts, not of metal; poles, not of metal, for power lines; non-metallic posts for electric lines; telegraph posts, not of metal; pins not made of metal