SF

nonmetallic construction and paving materials in the form of preforms and finished parts and components made of concrete and reinforced concrete, namely, concrete paving blocks, concrete blocks for construction of buildings and earth retaining walls, permeable concrete blocks allowing drainage, concrete flower containers, concrete gutters for surface water run-off, concrete curbs, concrete slabs; and spacers made of concrete, wood, paper, synthetic resins or other organic substances for laying down concrete slabs and blocks spaced from each other