Constantine I AE Follis, AE 20mm, 3,21gr; 309-337 AD. Siscia. 

Obv: IMP CONSTAN-TINVS AVG, bust left wearing high-crested 
helmet, holding spear and shield with horseman motif.
Rev: VICTORIAE LAETAE PRINC PERP, Two Victories standing 
facing each other, holding shield inscribed VOT PR over altar. 
Altar design Helv. 7j (a dot). 

Mintmark Gamma  SIS dot. 

RIC VII Siscia 61. Rare (R2).

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