Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
B1, formerly Bo1 is a Swedish second classpassenger car built by Kalmar Verkstad. The carriage belongs to the 1960s-cars family and was primarily used by the Swedish state railways, SJ between 1960 and 2006. The type remains in service in Sweden with private operators, including TÅGAB and Snälltåget. A total of 8 carriages remain in service in Sweden. Some carriages were sold to the Croatian state railways after their retirement from the SJ fleet.