From 1921 to 1923, a total of 2,236 Di 21 type coaches were built. 397 Di 21a-type coaches with slightly different interior fittings were also built. No other German passenger coach was ever built in such a large number. The coaches could seat 66 passengers in fourth class. They had a length over buffers of 13 920 mm and an 8,500 mm wheelbase, which ensured that they ran very quietly. When fourth class was abolished in 1928, the coaches were upgraded to third class and given the designation Cid 21.
• Road no.: 81 401
