The miniature buffet coach provided a small refreshment counter taking up the space of only a few seating bays in the coach, while retaining a good seating capacity for second class passengers. The counter could supply hot and cold drinks, snack and pre-packed food.

Initially intended for use on long-distance stopping trains by the blue/grey era customer demand for on-train catering had declined and the RMBs were found on many secondary and cross-country express trains.