US Patent 7908802 System for constructing tread surfaces

The present invention relates to a system for constructing tread surfaces comprising polygonal elements (1) where each element has a top surface and a number of substantially straight side edges arranged perpendicular to the top surface along the periphery of said top surface and that all side edges (2) are provided with a number of receiving openings (3) each opening adapted to receive and maintain a connector member, and that said elements (1), furthermore, along one or more of said side edges (4) are provided with one or more integrated and protruding connector members (5) which each are adapted to fit into said receiving openings (3).