T-30B

The T-30B was one of two prototypes (The other being the T-30A) designed to replace the obsolete T-38 amphibious light tank.

The T-30B prototype, sharing the T-30A's and T-40's chassis but simpler in construction and with heavier armor, was accepted as the T-60 scout tank, and began production in July 1941, just after the German invasion.

Image Sources
http://wio.ru/tank/tth.htm