Obverse
賞 - Award
reverse
海軍兵学校 - Naval Academy
In the center
勝て兜の緒を締めよ = 勝って兜の緒を締めよう
"After victory, tighten your helmet cords" i.e. even after a victory, prepare for the next battle and do not let your guard down.
At the bottom
通信 - Signaling/Communication
Original case.
Watch fob was made by Kishodo workshop https://asiamedals.info/threads/badges-labels-and-marks-of-kishodo-workshop-kishiyou.22007. Kishodo workshop was one of the main manufacturers of Naval Academy watch fobs.
Another example of cased signaling award badge.