The optional wagons 27 and 28 were delivered to the Mecklenburg-Pomeranian Narrow Gauge Railway (MPSB) by the Berlin wagon factory Glässing & Schollwer in 1911. They were later delivered to the Muskau forest railway (DR), after which they were transferred to the DFKM in Deinste in the summer of 1978.

Optional wagons could be used either as goods or passenger wagons. On the MPSB, they were mostly used to transport sacks of grain during harvest. However, if special trains had to be operated or the passenger car fleet was not sufficient, they were also used to transport passengers. For this purpose, benches were simply attached to the long sides.

The optional wagons were in quite good condition when they arrived in Deinste and so they could be used in the museum train straight away. From 1979, only car 27 was used for passenger transport, while car 28 served as an equipment and workshop car for the DFKM fleet. It was refurbished in 2023.