Non-metallic articles and materials for use in the construction of walls, retaining slopes and fences; non-metallic fencing; non-metallic fencing materials, including panels, posts and rails; non-metallic earth retaining structures; non-metallic walls, including non-metallic moveable walls; concrete articles and materials for use in the construction of walls, retaining slopes and fences, including reinforced concrete articles and materials; concrete fencing and wall components, including reinforced concrete fencing and wall components; concrete for use in fencing and constructing walls, including reinforced concrete; concrete panels, paving blocks, wall stone, blocks and palisades, including reinforced concrete panels, paving blocks, wall stone, blocks and palisades; reinforced concrete sleepers for use in the construction of walls, retaining slopes and fences; sandstones; sandstone articles for use in the construction of walls, retaining slopes and fences; sandstone fencing and wall components; sandstone for use in fencing and constructing walls; timber (other than unsawn timber); construction elements of timber; timber products for use in the construction of walls, retaining slopes and fences; timber fencing components; sleepers not of metal, including timber sleepers, concrete sleepers, and sandstone sleepers; and parts, fittings and accessories for the aforesaid goods, including non-metallic couplings