In 1978 Materfer presented a prototype vehicle that solved the problem of different voltages by providing a model that could be easily switched between the two voltages. Although Line B would remain an independent entity in the underground network. The trains were manufactured throughout the 1980s for use on Line E, however due to economic problems in the country at the time they never reached widespread use on the rest of the network as there was no funds available to purchase new equipment for all subway lines.
From a hint of "Bee" (NKP 765), colorful "Bees" (KCS), "Bees" w/ "attitude", to "Bees" that "sting" your eyes, in their own way they have "Bee" on display! Equipment that "Buzzes" with Yellow & Black colors! ("Bees" can still "Bee" entering this "hive"!)