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.
Tetrobol

(1) Histiaia c. 267-146 BC
Obverse: Head of nymph Histiaia right with wine-wreath
Reverse: Nymph Histiaia seated right on stern of galley, holding stylis; ornate apluster; IΣTI_AIEΩN, trident below
Ref: BMC Central p. 129, 52; SGCV I 2498...
(2) Macedonia c. 185-168 BC
Obverse: head of Maenad right wreathed with vine leaves and grapes, wearing necklace and earrings
Reverse: stern of galley right, star above; MAKE / ΔONΩN, M?
Ref: SGCV I 1384, SNG Cop 1292
(3) Phaselis c. 500-440 BC
Obverse: Prow of galley right; uncertain controlmark below
Reverse: Stern of galley left; ΦAΣ
Ref: SNG von Aulock-; Cf Heipp-Tamer 72
(4) Philip II | Philip III 323-315 BC
Obverse: head of Apollo wearing tainia right
Reverse: horseman riding right; ΦIΛIΠΠOY, M in wreath
Ref: Le Rider pl. 45, 33; SNG ANS 625-7;...