The "Formidable"-class ships made more extensive use of Krupp steel than the preceding "Canopus" class, with most of their side armour consisting of the stronger steel. They had an armoured belt that was thick and extended from the forward main battery barbette to the aft barbette; the transverse bulkheads on either end of the belt were 9 in thick forward and thick aft. The belt extended from main deck level ( above the waterline) to below the waterline. The ships' side plating forward of the belt was thick, while it was only aft of the belt. The ships were fitted with two armoured decks; the first was a flat deck that was thick, above the main deck, which was 2 in on the flat portion and increased slightly to 3 in on the sloped sides, where it connected to the belt armour.