Postumus Antoninianus, struck under Aureolus 267/268 AD at Milan mint.
Obv: IMP C POSTVMVS P F AVG, radiate, draped and cuirassed bust right.
Rev: VIRTVS EQVITVM / S (in exergue), Hercules standing right, right hand resting on hip, left hand holding lion's skin and club which rests on rock.
RIC 389; Elmer 619; AGK 113; Cunetio 2497
It has no silvering but an amazing portrait for these types and a rare reverse.