This coin is rated as an r5 and it actually is pretty rare. RIC only lists officina Γ, though I did have one from ∆; but I think it was unofficial. The real significance of this coin though is that the obverse legend has MAX in it. Constantine was awarded this title by the Roman senate shortly after his defeat of Maxentius in A.D. 313. This coin has the first use of the title MAX in the East for Constantine, and it is the only time it was used for the Siscia VLPP.
Constantine I
A.D. 318-19
IMP CONSTANTINVS MAX AVG; helmeted, laureate, cuirassed.
VICTORIAE LAETAE PRINC PERP; two Victories stg., facing one another, together holding shield inscribed VOT PR on altar .
In ex. ΓSIS
RIC VII Siscia 52