Passenger car model of the earlier Bai series, in ČSD livery approx. 1975-85. Passenger cars were produced in the Vagonka Tatra Studénka factory in the years 1969-75 in the qty of 520 units for domestic traffic to passenger trains pulled by a locomotive. Later, after 1983, they were renamed to the Bt-278 series, part of the car was reconstructed as Bt-283/288