For external communications it was intended to equip all vehicles with a radio set. For this it would have been necessary to rebuild the turrets, attaching a bustle at their back, to place the sets in. No vehicle had yet been so modified in May 1940. The commander could also give light signals to vehicles behind him by means of a small signal lamp placed on a small pedestal at the back of the turret. For internal communications he could use an electrical-optical installation, allowing him to give orders to the drivers by pushing one of four buttons: "Drive Forward", "Forward Halt", "Drive Backward" and "Backward Halt", causing the corresponding orders to light up on the respective driver consoles. The driver could more mundanely communicate with the outside world using a vehicle horn.