This armament Set is for Trumpeter's 1/350 USS Indianapolis (1945). This set includes two barrels types, nine 8"/55 (20.3 cm) Mark 9 main guns, and eight 5"/25 (12.7 cm) secondary guns. It also includes resin trunnions, one for each turret. These trunnions are required to allow the use of the machined aluminum barrels for the 8" guns, as the kit trunnion is a two-part assembly that is not conducive to aftermarket barrels.