Old Small Copper Coin

I have a sterling silver pendant that was made in Israel that is holding a small copper coin. The obverse is really worn and it's hard to make out anything other than a right-facing bust. The reverse is a little clearer but I'm at a loss as to the characters and how to describe it for a search.

It measures 15.4 mm and I would guess about 0.6 mm thick.



Does anyone know what this is?

Thanks, all!

: CONSTANTINVS MAX AVG. GLOR-IA EXERC-ITVS/ -|-// SMAN.
Two soldiers