 The mountings were automated and stabilised with radar control and 720 rounds were stored per mounting.Initially British 4.5 inch twin Mk 6 mountings were considered but rejected due to complexity, manpower requirements (19 men per mounting) and dependence on hydraulics for operation.The close-range anti-aircraft armament was reduced to a single Bofors 40 mm gun due to the heavy top weight of the 120 mm mountings.