The U series was originally a narrow-gauge steam locomotive of the k.k. Austrian State Railways (kkStB) for a gauge of 760 mm. It is one of the most widely built narrow-gauge locomotives in Europe. The locomotives proved to be so reliable that they were procured in large numbers by nearly all operators of narrow-gauge railway lines in Austria and were constructed by several locomotive manufacturers. The last example of the U series was built in 1922 for the StLB, long after more modern locomotive types had already been introduced. Those U series locomotives that passed into the possession of the ÖBB after World War II were designated as series 298 with two-digit identification numbers starting in 1953. Due to their large numbers, many machines of this type are still operational today at museum and tourist railways. Some examples have also been set up as locomotive monuments. Locomotive 3 of the Lower Austrian State Railways was photographed in its livery shortly before being put into service in 1902, positioned in front of the factory gates of Krauss Linz to allow the photographer to take an optimal work photo. Our model accurately reflects this livery. Later, the locomotive was designated U 7.