ENThe Type 91 Hand Grenade (九一式手榴弾 Kyūichi-shiki Teryūdan) was an improved version of the Type 10 fragmentation hand grenade/rifle grenade of the Imperial Japa...
ENThe Hiro H4H (or Hiro Navy Type 91 Flying Boat) was a 1930s Japanese bomber or reconnaissance monoplane flying boat designed and built by the Hiro Naval Arse...