This kit represents those carriages built after the prototype vehicle (S15000) which had slightly different internal dimensions. Four first class and three second class compartments were separated by a cross vestibule with a door in the compartment side. As well as two doors each end there were two extra doors on the corridor side. The central third class compartment had a top-hinged opening window to admit stretchers. D126 had six seats per compartment with retractable armrests; D128 third class compartments had eight seats.
The photos show carriages fitted with B1 bogies.