This was a prototype during the work with a new tank in the years 1938-1939. It was developed from the experimental vessel BT IS (1936-1938) and had got sloping armour on all sides. It was the forrunner to A 32 (see this tank) and the armament was the same as the contemporary BTs - a 45 mm gun. The all over design was similar to the T 34 to come with one exeption: The wheels were still four in number compared to five with a diameter 10 percent smaller. First and last wheel kept its place and the other three were distributed (slightly uneven) inbetween. Its armour was thinner than the T-32.