Watch List notes:

SICILY. Syracuse. Hieron II, 275-215 BC. Heptachalkon (Silver, 14 mm, 1.40 g, 7 h), circa 216-215. ΣΥΡΑΚΟ - ΣΙΩΝ Tripod with top and three raised ring handles; border of dots. Rev. XIIΠ (= chalkoi 2 + 5 = 7) with monogram of ΑΦ below. Buceti 1273 = CCO 315 (D3/R2, this coin). Extremely rare. A fascinating coin, well-centered and lightly toned. Some roughness, otherwise, good very fine.
From the "Collection sans Pareille" of Ancient Greek Fractions, ex Auctiones 27, 10-11 December 1996, 130.

The idea of a coin valued at 7 chalkoi is quite an odd one; but then, the denominations struck under Hieron II were quite unusual. That is certainly why they found it necessary to place the denomination on the coin!