I just got this campgate from Sirmium, they are fairly rare.
Constantius II
A.D. 324- 325
19mm 3.1gm
FL IVL CONSTANTIVS NOB C, laureate draped and cuirassed bust left.
PROVIDEN-TIAE CAESS, campgate with two turrets, star between them.
In ex. SIRM
RIC VII Sirmium 53