Bronze follis, 24mm, 6.32gm, issued AD 309-312 Ostia mint.
Obv: IMP C MAXENTIVS PF AVG, Laureate head right.
Rev: AETERNITAS AVG N, Castor and Pollux, wearing caps, nude, chlamys draped over shoulders, standing facing each other, both leaning on sceptre and holding bridled horse.