20 Installation material, not of metal, namely, non-electric cable screw connections [not of metal], also as divided cable screw connections; non-electric ducts for cables, not of metal, also in the form of wire trays and in the form of drag chains; parts for non-electric ducts for cables, not of metal, also in the form of wire trays and in the form of drag chains, namely, covers for ducts of cables, hinge systems, coupler plates, partitions, angular pieces, t-connectors, seals, clips, installation profiles, mounting angles, bending protection parts, blind plates, flanges, caps, holding parts, nuts, bolts, screws, threaded bars, convertors, retainers, edge protections, safety cables, telescopes, pendants, support foots, clamps, wall brackets, anchors; parts for non-electric cable screw connections [not of metal], namely, screw bodies, double nipples, reducer parts, extension parts, sealing inserts, cable inlets, divisible flange systems, shielding contact elements, conical discs, breather drains, connection threads, blind plugs, washers, flanges, flange angle parts, frames, pressure equalisation insert plugs, sealing plugs, screw plugs, coupling pieces, earth tags; parts for non-electric cable screw connections [not of metal], namely, lock washers of plastic, pressure screws, angular pieces, cable inlets, antikink parts, bending protection parts, clamping rings, collar bands, spiral springs, nuts, clamping nipples, earth tags