Slab tracks, or non-ballasted track structures, require fastening systems directly attach to the concrete slab, and must meet special requirements to deflect the forces generated by a rolling train. Vossloh has developed the DFF series, a line of highly elastic direct fixation fasteners, for optimum performance in slab tracks used in urban transit and conventional rail. These direct fixation systems provide a single support point in slab track with its screw-dowel combination for anchoring, and are equipped with Vossloh’s patented Cellentic rail pad, which is made of a highly-elastic elastomer, that provides the essential flexibility required in direct fixation fastening systems.