 In order to reduce the noise, Prairie-Masker was installed after the 3rd ship and was also equipped with the 1st and 2nd ship at a later date.From DD-129 onward, steel replaced aluminium for key elements of the superstructure including the bridge from the viewpoint of resistance and durability.However, due to this design change, the ballast had to be installed, the displacement increased and the movement performance was deteriorated.