Early on, some freight wagon types began to be standardised in Switzerland. These were then also procured by all private railways in order to improve repair and spare parts inventory. Among them were covered freight wagons with an axle base of 4.5 m and a frame length of 7.10 m. Later, the wheelbase was increased to 5 m to improve the running characteristics. In this form, the wagons designated K2 were procured by SBB in large quantities.
