The BT tank was produced in over 7.000 units from 1932 to 1941 in basically 4 models (2, 5, 7, 8) with increasingly thicker armour. They were able to go on railroad tracks as well as on roads or in the terrain. With their thin armour they were very fast (BT= Bystrochodnij Tank= fast tank) and had the mission to be active in large numbers on the battlefield, supporting infantry. A chassis (without a turret) imported from the USA in 1931 was the prototype and the individual wheel-suspension was to survive in later tank models as well. The last BTs were in action in the winter of 1942-43 in the Finnish front and by then an easy target for the modern anti tank guns. Nicknames were: Betka, Betushka.