The Half-Stater denomination
The half-stater was an ancient denomination worth half of a stater. It was struck in both gold and silver.

SIlver coins struck under Croesus with an approximate weight of 5g are typically referred to as both half-staters and as sigloi.

As a gold denomination, it is used for coins with an approximate weight of 4.25g, often struck in by Celtic tribes or in Calabria or Macedon.
Half-Stater

(1) Croesus 561-546 BC
Obverse: Confronted foreparts of a lion and a bull
Reverse: Two incuse square punches
Ref: SNG von Aulock 2877