The DB replaced the original wooden benches, in many cases, by upholstered seating.
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In a succession of procurement programmes, a further 517 4th class, all-steel coaches (440 in Austauschbauart form) were acquired in 1927/28, followed by a total of 5,009 coaches of 2nd, 3rd, 4th, 2nd/3rd and 3rd/4th classes (of which 3,377 were Austauschbauart versions) from 1928 to 1930, so that by 1930 more than 8,250 coaches had entered service.
For the rolling stock formerly used on the German railways, see Donnerbüchse.