Greek coin

Dear Sirs:
The purpose of this letter is to ask for your assistance in the identification and evaluation of a coin or medal, whose pictures I am enclosing in the DropBox link. It is a metallic coin of about three centimeters of diameter, and about three millimeters thick in the top part and only two in the bottom. It seems to be from ancient Greece, presenting in the front side a figure that somebody has mentioned represents the God Zeus. As you may see, in the photographs of the back side of the coin, it has some interesting inscription. It is clear that it is a one piece object, having at the top a small ring. The color of this coin is bronce-like. We know that back on 1978, when it first appeared on my family, it was completely dark, almost black, but somebody at that time decided to clean it with a metal cleaner.

The pictures can be found here:

https://www.dropbox.com/sh/ttzxyhbjlbmtiqs/AAAjDmLNQDIp-NtPw0WB38H1a?dl=0

I shall indeed appreciate all the information you could provide me about this interesting coin or medal.
Looking forward for your reply, I am glad to anticipate my gratitude and send you my best regards.
Jorge