The "IS-4" is a Soviet heavy tank, also known as Object 701, developed starting in 1943 and produced from 1946 to 1949. It was derived from the IS-2 tank and featured improvements such as thicker armor and a longer hull. However, it was overweight and sluggish, making it less practical compared to other tanks like the IS-3. Fewer than 250 IS-4 tanks were built, and many were stationed in the Russian Far East. The IS-4 is notable for its powerful 122mm gun, strong armor, and a distinctive rear transmission and engine design. It was produced too late for World War II and eventually became somewhat obsolete, with some tanks used as pillboxes on the Chinese border during the 1960s.