Maxentius (306-312) AE Follis (Bronze, 24mm, 6.63g) Ostia, 309-312.
Obv: IMP C MAXENTIVS P F AVG, laureate head right /
Rev: AETERNITAS AVG N, Castor and Pollux facing one another, holding horses to centre and spears to outside, MOSTP in exergue.
Ref: RIC 35.