Constantine AE Follis. 

Obv: IMP CONSTANTINVS PF AVG, laureate cuirassed bust right 
Rev: PRINCIPI IVVENTVTIS, Constantine standing facing, head left, 
 in military dress, holding standard in each hand, S-A across fields
Mintmark: PTR

RIC VI Trier, 781, rated C2.

With permission of Roma Numismatics, June 2009