Petropavlovsk-class battleships
... that each of the three Russian Petropavlovsk-class battleships had a different type of steel armor?
... that each of the three Russian <b id="mwD3c"><a class="mw-redirect" href="./Petropavlovsk_class_battleship" id="mwD3g" rel="mw:WikiLink" title="Petropavlovsk class battleship"><i id="mwD3k">Petropavlovsk</i>-class battleships</a></b> <i id="mwD3o">(Poltava pictured)</i> had a different type of steel armor?