Watch List notes:

60 asses circa 209-208, AV 3.35 g. Bearded and draped head of Mars r., wearing Corinthian helmet; in l. field, mark of value, 9X. Rev. Eagle standing r., with spread wings, on thunderbolt; in r. field, anchor. Below, ROMA. Bahrfeldt 4b. Sydenham. 236. RBW 185 (this coin). Crawford 50/1.
Extremely rare, twenty-one specimens known of which only five are in
private hands. Minor marks, otherwise very fine

Ex Glendinings 7th July 1971, 146; Triton III, 1999, 812 and NAC 61, 2011, RBW part I, 199 sales.