The Tetrobol denomination
A Tetrobol is an ancient Greek denomination worth 4 obols - 2/3rds of a drachm.

It was struck in both bronze and silver.
An AE Tetrobol struck 180-170 BC in Alexandria
Obverse: Wreathed head of Isis to right

Reverse: Eagle standing to left on thunderbolt; ΒΑΣΙΛΕΩΣ ΠΤΟΛΕΜΑΙΟΥ around, monogram to left

Diameter: 26 mm
Die Orientation: 11 H
Weight: 16.03 g
No notes for this coin
Svoronos 1384; SNG Copenhagen 279-87