Watch List notes:

MACEDON. Uncertain mint. Early to mid 5th century BC . Diobol (Silver, 10 mm, 1.31 g). Head of a horse to right, with a prominent mane. Rev. Irregular incuse square. Apparently unpublished, but see: Münzen und Medaillen FPL 451, January 1983, 14 (uncertain Macedonian mint); Helios 6, 2011, 399 (Sermylia ?); Numismatica Ars Classica 54, 2010, (Maroneia ?); Numismatica Ars Classica 82, Falm Collection, 166 = Hauck & Aufhäuser 12, 1996, 117 = Demeester 100, (Kyme, Aeolis!). Very rare. Well-centered, nicely toned and struck in high relief. Extremely fine.
From the "Collection sans Pareille" of Ancient Greek Fractions.