The two-car X1 multiple unit was procured by the Stockholm Metropolitan Transport Authority to serve the Pendeltåg (“shuttle train”) journeys. It was based on the three-car X6, which was developed to replace locomotive-hauled trains. Only three sets of the X6 were built, but initially 90 and later another 14 X1s were built instead. One of the two cars was powered on all axles and four sets were usually coupled together, which were almost 200 meters long and offered space for 784 passengers. When there were fewer passengers, two sets were often driven together. With the vehicles of the class X10, which were introduced later, multiple working was also possible.

As usual for multiple units from this period, the car bodies were rectangular. The lateral outer walls were made of corrugated steel and each had three doors for quick passenger exchange. The Stockholm subway was the inspiration for the interior design and five seats per row were installed, each facing each other in groups. Over the years, the interior has often been remodeled and modernized, as is common with high-traffic commuter vehicles with high levels of wear and tear. The technical equipment of the vehicles was converted in the eighties due to a lack of winter resistance. As part of the development of the X2000, a train was equipped with a different gear ratio and tilting technology, which reached 222 km/h. The X1 was replaced by the X60 (Alstom Coradia Nordic) from 2004 and was completely gone by 2011.