Material: Base: steel plate, zinc plated. Damping elements: Polyamide (damping elements only for travel-wheel system with Hydropur-tyre travel wheel). Version G: for travel-wheel system with cast wheel. Without damping element. Version K: for travel-wheel system with Hydropur tyre. With damping element. Consisting of: roller bracket, bearing, damping element and mounting bolts (damping element only for version K). Two sizes for travel-wheel system size 200 or 250. The horizontal guide-roller arrangement is used for low-friction guidance and to precisely achieve individual track gauge dimensions. The guide roller is e.g. recommended for flanged wheels (version G) running on narrow tracks. The guide rollers are only used on one of the rails.