Watch List notes:

Postumus. Romano-Gallic Emperor, A.D. 260-269. AE (double?) sestertius (31.13 mm, 14.59 g, 7 h). Cologne mint, struck A.D. 261. [IM]P C M CASS LAT POSTVMVS P F AVG, radiate, draped and cuirassed bust of Postumus right / [LAE]TITIA // VGA (sic.), galley with seven rowers and helmsman rowing left over field of waves. RIC 143 ; Hunter 123. Fine, toned metal atop devices, blackish-green patina in recesses and fields. 

on squarish flan which was likely a re-purposed Antonine era sestertius, but without enough visible undertype features to say exactly whose it was