Abstract: The invention provides screen elements of polyurethane, or a material having similar characteristics, having metal reinforcing rods embedded in and extending only in a single direction and across the full width of the screen element between lateral support zones. A plurality of screen elements can be replaceably secured to a complementally shaped support frame member by a combined elongate fastening formation formed by two abutting elongate fastening formations respectively of two screen elements in edge-to-edge abutting relationship. For this purpose each screen element has an elongate fastening formation along the under side of each of its two opposite lateral edges, in addition to one or more securing formations at each end to secure screen formations together in end-to-end relationship. The invention also provides a screen deck consisting of screen elements secured to support frame members, as described above.