• The BT-7 was the last of the BT tank series of Soviet cavalry tanks that were produced in large numbers between 1935 and 1940. They were lightly armoured, but reasonably well-armed for their time, and had much better mobility than other contemporary tank designs. The BT tanks were known by the nickname Betka from the acronym, or its diminutive Betushka. [2]
    The successor of the BT-7 Tank would be the famous T-34 medium tank, introduced in 1940, which would replace all of the Soviet fast tanks, infantry tanks, and medium tanks then in service.
    http://2daydesign.ru/project/3d-model-tanka-bt-7/