Constantine I AE follis, Siscia. 

Obv: IMP CONSTANTINVS AVG, Helmeted laureate, cuirassed 
bust left, holding spear and shield.
Rev: VICTORIAE LAETAE PRINC PERP, Two Victories facing,
holding shield inscribed VOT PR on altar with design
Helvetica 7S (an X). 

Mintmark BSIS.
RIC VII Siscia 56, rated R4.

With permission of www.slaveycoins.com, March 2012.