20 cm/50 3rd Year Type naval gun
Third year type 20 cm/50 caliber guns formed the main battery of Japan's World War II heavy cruisers. These guns were also mounted on two early aircraft carriers, the Kaga and the Akagi before their 1935 reconstruction. Wikipedia
Maximum firing range: 29 kilometres (18 mi)
No. built: ~300
Shell: 1 GÔ (Mark 1): 110 kilograms (240 lb); 2 GÔ (Mark 2): 126 kilograms (278 lb)