They were introduced in the Bilbao-Plentzia railway in 1927, and were later operated by Ferrocarriles y Transportes Suburbanos, Euskotren, Metro Bilbao and Euskal Trenbide Sarea until 2012.

[2] The railcars were built by Carde y Escoriaza [es] in Zaragoza, while the bogies and electric components were manufactured by Brill and AEG respectively.

[6] All passenger railcars, with the exception of MAB 5, were eventually refurbished with metal bodies[3] replacing the original ones made of teak wood.

[2] The freight railcars were also refurbished with metal bodies and converted for passenger service in the 1950s, they were concurrently renumbered MAB 13–15.

[7] Their original wooden bodies were used to refurbish three Allsthom railcars acquired from the Toulouse-Castres railway [fr], which took over the MD 1–3 numbering.