Developed in 1937–1938 under the "20-ton vehicle" project and was intended to replace the D2. The project included two turret variants: with a 37-mm or a 47-mm gun. By 1938, two vehicles were built for trials. Never saw mass production.
Time for the successive autoreloading of each shell into the magazine.
The technical characteristics shown are for the Siege mode
Characteristics are specified for a vehicle with crew members trained to 100%.