Third year type 20 cm/50 caliber guns (五十口径三年式二〇糎砲, gojūkōkei sannenshiki ni-maru centi-hō) formed the main battery of Japan's World War II heavy cruisers. These guns were also mounted on two early aircraft carriers. The typical installation was ten 20 cm/50 guns; although Tone-class cruisers carried eight while Furutaka and Aoba-class cruisers carried six. After modernization, Akagi carried only six.