Badge of similar design https://asiamedals.info/threads/tank-units-commemorative-badges-and-watch-fobs.23221/#post-346992
Windth 33.9 mm.
Reverse
優秀章 - Excellence Badge
japanese army tank crew excellence award badge
japanese army tank crew excellence award watchfobjapanese army tank crew excellence badge
japanese army tank crew excellence watchfobjapanese imperial army watchfobjapanesetank award badge
japanesetank award watchfobjapanesetank badge
japanesetankwatchfob
優秀章
大日本帝国陸軍戦車兵優秀章
陸軍戦車兵優秀章
commemorative badges and watchfobs
imperial japan army tank school
imperial japan army tank units
japanese badge with tankjapanese badges
japanesetank badge
japanesetankwatchfobtank
戦車バッジ
輕装甲車訓練所章