After the nationalization of the private railways had the SBB in their fleet a wide variety of car types, which were not up to the new requirements. Based on positive experiences with wagons with axles of 9.00 m, standards were set for the new types to be procured. For Nebenstrecken the biaxial second class carriages were included in the program.

The cars were built as transit cars and had fabric-covered upholstered seats. In Wagenmitte there was an abortion. Leaf springs of 2.50 m length gave the vehicle a very great smoothness. The two large compartments each had 22 seats for smokers and nonsmokers.

Registration numbers: B3 3754 - 3815

From 1947 all cars B3 3010-3071. In 1960 still 27 cars in operation