The Siglos denomination
The Siglos was a coin denomination in the Persian Achaemenid Empire, and was roughly equivalent to 7½ Attic obols. It was struck in silver.

In more understandable terms, it generally weighed 5.4 grammes, and was struck from circa 520 BC to 330 BC.
Siglos

(1) Achaemenid Empire 455-420? BC
Obverse: hero or king holding bow and dagger right
Reverse: incuse square; crescent countermark
Ref: Carradice type IV (early) A
(2) Achaemenid Empire 510/505-486 BC
Obverse: Great King right bearded and crowned kneeling-running, drawing bow, quiver at shoulder
Reverse: incuse square
Ref: Carradice type II: Carradice plate ...
(3) Croesus 561-546 BC
Obverse: Confronted foreparts of a lion and a bull
Reverse: Two incuse square punches
Ref: SNG von Aulock 2877