IS 4 (Object 701) was an experimantal tank armed with the cannon D-10. The vehicle was tested during the summer and into the fall of 1944. The results did not convince the military astablishment to go further in the development and the project was stopped. It was an attempt to develop a heavy tank for the last period of World War II and for the post-war period. The IS serie continued as the heavy MBT and the prototype to be aproved of by the army was the IS-10, later to be called T-10. A surviving unit can today be seen at the Kubinka museum.