A further development of the O-I with improved anti-tank guns. The military command's plan was to improve the earlier models and achieve a higher level of armor protection on the vehicle. Existed only in blueprints. No finished prototypes were built and the vehicle never saw action.
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%.