Watch List notes:

WESTERN ASIA MINOR, Uncertain. 4th century BC. AR Obol(?) (10mm, 0.80 g, 7h). Laureate head of Apollo right / Tripod, with fillets hanging at sides, within linear square; IPON to outer left. Numismatik Naumann 53, lot 250 (Kolophon?); otherwise unpublished in the standard references. VF, toned, granular surfaces. Extremely rare.

Unlike the Naumann piece, the fields are fairly clear on this piece, suggesting that there are no other letters on the right side of the reverse, which makes identifying the issuing mint even more mysterious.