Watch List notes:

Rome, libral standard based on the Roman libra, AE As, Aes Grave, (approx. 350 g), (280-276 B.C.), obv. Janus-like double head of the Dioscuri, rev. Mercury head with winged petasus left, (S.519, Syd. 8. Crawford 14/1, Haeberlin p. 93 ff., plate 38, 1-7). Green patina, minor piece from edge, nearly very fine and very rare.

Probably the earliest Roman As, recent research suggests a slightly later date.